The answer is a qualified yes--to the Ruger products fitting without a lot of additional work. While it is true that Colt and clones can often vary (more), and therefore most custom makers want you to ship your gripframe for exact fitting--my experience has been pretty straightforward fitment with most major Ruger gripmakers without having to do that. They have jigs in the most popular gripframes--Blackhawk (large frame Vaquero) and New Vaquero (same as the new Flattops) etc, which should make them pretty close. The "qualified" part is that it is still not guaranteed to fit right out of the box, since grips/gripframes *can* vary.
What I've found is on a certain small percentage--at most the locating pin can be off just a skosh from one gun to another (ie vary from the gripmakers' jigs) and so you may need to epoxy the existing hole in the panel(s) and slightly relocate (re-drill) the hole on your new grips. On others you may just need to ream out the hole in your panel(s) very slightly (talking 00ths or 000ths) if they don't quite want to fit perfectly. (Warning: don't force the issue.too much, risking cracking your grip). If it just won't fit with some modest tunkering, see above re the locating holes--or in the worst case, return the grips.
A few top custom makers for Rugers are Carl "Private" Schultz
www.privatescustomgrips.com and Cary Chapman
www.clccustomgrips.com .
In the
www.shopruger.com site, there are a few which will work (which are probably the ones you mention). IIRC, the non checkered Rosewoods listed for the Blackhawk/Vaquero (XR3-Red) are actually laminates. Mine fit perfectly. Also, the "black" (actually gray and black) laminates listed for Single Six with square triggerguard and 10" barrel only, are mislabeled (gun/limitation described doesn't exist in a SS) and actually are for any regular XR3 Red (large frame Blackhawk, Vaquero, short barreled SBH, and Single Six). Also a good fit in my experience. Contact the Ruger New Hampshire office directly to verify this information re current accuracy.
One last note, yes, on a small percentage, some sanding and re Tru Oil'ing (etc) may be required if the grips are proud of the metal--"wood proud" (not a whole lot you can do if they're "metal proud"--grips too small)
However it can be deceiving... on many grips, initial fit even if the locating holes seem ok, may be off and though not requiring any work on the grip panels themselves, you may need to play with them and reposition several times..again not necessarily requiring any alteration work to the grips themselves. Sometimes--actually often--there's more positioning, loosening and retightening of these than you might think there will be.