Shadi .............. Altamont appears to have a good reputation, but if you're lookin' for that "final touch of perfection" as you stated in your OP, I'd seriously step it up a notch and consider the precision fit and finish of "custom" grips for your Vaquero. They can be made in any desired thickness, tapered or flat bottoms, and a variety of grip materials.
If this is a viable option, I'd highly recommend two superb custom grip makers who specialize in Ruger SA's as follows:
Scott Kolar at skgrips.com and Cary Chapman at clccustomgrips.com. Give either one a try, you won't be disappointed.
the Shadow
P.S. If you like genuine Ivory but don't want to spend $500.-$600. ask them about Sheffield's antique paper micarta. Quality paper micarta makes real good lookin' grips, are very durable and look and age like real Ivory.