Geeze, here goes, Philip...
Hopefully, you got some brass with your Sharps when you made the deal. New 45/110 (45 2 7/8ths Sharps Straight) brass may be a bit elusive to find currently...and expensive. Without getting into the basics to build custom, handloaded ammo geared specifically for your particular rifle, you can have some fun with it, safely, while you're learning to build the best accurate rounds for your rifle. And believe me, it takes time, research, $$, the right equipment, and lots of testing at the range.
Looks like you have "the knowledge" on how black powder works with your current m.l. arsenal (and a Rifle Shoppe Baker? Very cool!), and about how fouling plays in those guns. In a black powder cartridge rifle using strictly black powder (no duplexing here) it's all about fouling control, and a properly greased bullet that fits your bore properly (nothing about paper-patched bullets here, just grease-grooved bullets). Those three things are key; fouling control, bullet lube, and the right bullet. HiBC got into info you'll need to read again, too, as you begin your journey. Above all, don't get discouraged, and I'll also say this; if you can stick with this reloading project you're about to take a shot at (pun intended), and end up with quality, custom, accurate ammo using black powder and cast bullets, you'll be able to say loading for anything else is mere child's play, and that's just and only my opinion. So, if I were you (knowing what I know now about this business), and not ever having used a reloading press along with all the other equipment you'll need to acquire down this trail, this is what you MIGHT do to have some fun IF you have some fire-formed brass from your rifle, that hopefully you got with your "new" Sharps.
First, get a good case length guage to make sure your cases aren't too long. If your chamber is cut correctly, 2.8" is maximum for case length in a 110.
Buy a box of 50, pre-lubed, 525 grain Postell bullets, sized @ .458" with a 20:1 lead-tin alloy. Should be fairly easy to find; I'll bet Buffalo Arms has them. Call them yet? Also, if you order bullets from BACO (Buffalo Arms acronym), also get a bag of .45 cal., .060" veggie wads.
Get a hand priming tool; I have a Lee hand tool that I use occasionally, they're fairly cheap (used to be anyway). That's a good first tool to get (IMO), along with your case length guage/caliper. For now, any large rifle primers will do.
Then, of course, black powder. Good ol' 2fg GOEX will serve you very well to start with.
IF you have CLEAN, FIRE-FORMED cases of the correct length for your 110, prime them, measure out 100 grns. of b.p., dump it in the case and put one of the veggie wads over the powder, then tamp that wad down tight against the powder; use an end piece of an old 7/16ths ramrod for the tamper; works good (bet you have that...).
Wipe off the base of the bullet to make sure there's no bullet lube present there. And now this is where it may or may not be "iffy." You SHOULD be able to "finger seat" that .458" Postell bullet in the case mouth to push it TIGHT against the powder charge, with just your fingers. I've done this many times with my 45/70 Sharps. Using this method, you don't need a die set at all, just the priming tool. To test this "finger seating" business, take one of your Postell bullets, wipe it completely clean of all grease, and see if it will fit in the case mouth of an empty case; you'll know then if the method should work prior to having all your cases prepped with primer, powder and wad. A little resistance on trying to seat the bullet isn't a bad thing, either. Just keep in mind that you don't want to deform the bullet whatsoever when seating; I've used a leather pad to seat bullets in the palm of my hand for some extra help.
NOTE: You may have a bit of trial and error to find the right powder charge to use if 100 grains won't allow you to seat the Postell bullet so that all the grease grooves are covered/contained in the case AND TIGHT AGAINST THE POWDER CHARGE; NO AIR SPACES. Once you've got a round loaded as such, you should be ready to take it to the range. Your new rounds SHOULD chamber properly with a bit of freebore; that's what you want for these "fun" rounds. But first, you'll also need this stuff:
A range rod with a proper .45 cal. jag, appropriately sized 100% cotton cleaning patches, some black powder solvent, and a blow tube, preferably made from one of your fire-formed cases. Blow tubing is an art unto itself; more stuff to learn! Remember the comment on fouling control? That's all about the blow tube, unless you swab between shots, and that's something you can find out about later. Too much here already! Then, when you get home, you have to clean your rifle, and your cases. Rifle's easy to clean, cases take way more time. Won't get into that here, either. As Old Bear Claw Chris Lapp told the greenhorn Jeremiah, "You've got work to do." YouTube will show you an awful lot; this is only a beginning; stay after it and don't get overwhelmed. Learn all you can, and question what I've put down here. All this stuff has worked for me when I started out.
BTW, I have two Sharps rifles, both Shilohs, one a Hartford model in 45/70 (my hunting Sharps), and 45/90 long range express I use for the gong games I play a few times during the summer months. I use black powder exclusively in both rifles, cast bullets I mould myself, and the blow tube method with all my shooting done competitively. Since 2001, I've only missed two "Quigley" matches; always an experience that anybody who's into B.P.C.R. should participate in at least once (IMO). Quite the experience, every year.
One last comment here, does your buddy with the 45/90 reload? Sounds like there might be your first source for info on your journey. Also, if you can find anyone in your area that's into B.P.C.R. seriously, find that guy! There's so much involved, especially if you've never done any cartridge reloading....yet!
Good luck, Philip!
I also hope if anyone else on TFL can add or subtract to what I've posted here, have at it.
And again;
www.buffaloarms.com