Howdy Again
Lets talk about fixed sights first:
"Full Power Loads" are in the eyes of the beholder.
All the Italian replicas are proofed to standards slightly higher than American SAAMI standards. They are proofed for standard ammunition that you find on the shelves of most stores. No, they are not capable of digesting +P loads, but they are not restricted to 'Cowboy Ammunition' which is generally loaded to a slightly lower level.
The Ruger New Vaquero is not as big and beefy as the older 'original model' Vaquero. Like most Ruger revolvers, the older 'original model' Vaquero could safely digest loads in most of the loading manuals referred to as Ruger Only loads. That model is no longer made. The currently available New Vaquero is slightly smaller than the 'original model'. Ruger suggests limiting it to SAMMI spec ammo. Just like the Italian replicas. There are lots of arguments about how much pressure the New Vaquero can actually handle, but I'm not going there. If you buy a New Vaquero, best to stick with the off the shelf stuff.
Adjustable Sights:
The Ruger Blackhawk series has been built on a larger frame than the old Colt Single Action Army for many years. Because the frame is larger, the cylinder is larger with more metal between the chambers. These revolvers are very strong and are capable of digesting Ruger Only loads with no problem, if you can take the recoil. There are a few Blackhawks being made on a smaller frame now, and they should not be fed Ruger Only loads. But most Blackhawks are built on the larger frame (the same size frame the old 'original model' Vaquero was built on) and can digest Ruger Only loads and everything else less powerful.
Traditionally, single action revolvers had what is often known as a 'four click' mechanism. When you cocked the hammer, there were four distinct clicks the mechanism made. 1. 'safety cock', 2. half cock, which freed the cylinder to rotate for loading, 3. the bolt popping up against the cylinder, and 4. Full cock with the cylinder locking up in battery ready to fire. These revolvers WERE NOT safe to carry fully loaded with a live round under the hammer. Even if the hammer were pulled back to the 'safety cock' position, if the hammer spur was struck a strong blow, the internal mechanism could break and the firing pin could be driven into a live cartridge under the hammer, firing the round. Dropping the gun on its hammer was often enough for the revolver to discharge. So the old style revolvers, which include real Colts as well as most of the Italian replicas were only safe to carry loaded with five rounds in the cylinder, with an empty chamber under the hammer.
Way back in the 1970s Ruger completely redesigned their line of revolvers, incorporating a Transfer Bar into the design. This meant they were completely safe to carry fully loaded with a live round under the hammer. If the hammer was struck, it could not physically reach the frame mounted firing pin to fire a cartridge.
ALL Ruger revolvers made since the 1970s have a transfer bar inside, both fixed sight versions and adjustable sight versions. So they are ALL safe to carry fully loaded. These are usually referred to as New Model Rugers.
About two years ago Uberti redesigned their line of single action revolvers to include a retractable firing pin in the hammer. No more four clicks, only three. The firing pin is retracted in the hammer just enough so that it cannot reach the primer of a live round under the hammer. Only when the trigger is pulled does the firing pin extend far enough so it can fire a cartridge. This style of single action revolver is safe to carry fully loaded, if the hammer is struck while the hammer is down, nothing will happen except maybe banging up the finish of the revolver.
As I said, this is a very new development, and it only applies to single action revolvers made by Uberti. The other brands of Italian single action revolvers mostly still need to be loaded with only 5 rounds with an empty chamber under the hammer.
Clicks: Some guys make a big deal about the number of clicks. They think that four clicks is the only proper amount of clicks a single action revolver should have. The new Ubertis only make three clicks, a Ruger only makes two, one when the bolt pops up and one when the hammer goes to full cock. I have many different types of single action revolvers, real Colts, Ubertis, and Rugers as well as a few other brands no longer made. I can tell you that the only time I can actually hear the clicks is when I am pretending to shoot bad guys at night watching TV. You never hear that real slow ratcheting of four clicks in real life that you do in the movies.
Anyway
Fixed sights: Italian replicas or Ruger New Vaqueros.
Adjustable sights: Ruger New Model Blackhawk.
Maximum SAAMI spec loads, all of the above.
Ruger Only loads: Ruger Blackhawk.
That's pretty much it off the top of my head.
P.S., not a hunter so I can't help you with that. I like most barrel lengths, 4 3/4" (Colts) 4 5/8" (Rugers), and 7 1/2", (Colts, Clones, and Rugers.)
I don't care for the 5 1/2" length, just don't like its appearance. Purely a personal opinion, nothing more.
A few photos:
My favorite pair of single action revolvers, two 2nd Gen Colts. The one at the top has a 7 1/2" barrel, the one at the bottom has a 4 3/4" barrel. Both chambered for 45 Colt, this is the pair I shoot most often in CAS, and I only shoot them with cartridges loaded with Black Powder.
New Model Ruger Single Action revolvers. All are equipped with transfer bars and all can be safely loaded with six rounds. Left to right, 45 Colt/45 ACP Blackhawk that I bought many, many years ago. It came with an auxiliary cylinder for 45 ACP. Next is a blued 'original model' Vaquero chambered for 45 Colt (no longer available). Next is a pair of Stainless 'original model' Vaqueros, chambered for 45 Colt. (also no longer available). Finally on the far right a pair of New Vaqueros. This pair happens to be chambered for 357 Magnum.
These are all Three Screw Rugers. Notice they each have three screw heads showing on the right side of the frame, as opposed to two pins with the New Models above. These have not been made since the 1970s, before Ruger redesigned his single action line to include a transfer bar. Like a Colt, these are only safe to carry loaded with five rounds with an empty chamber under the hammer. Left to right, a 44 Magnum Flat Top, a 357 Magnum, a 357 Magnum Flat Top, and three 22 Rimfire Single Sixes.