GunHawk,
Have you ever shot a Ruger with a rd butt grip? I'd suggest you do that first, especially in 45.
I found that the rd butt caused the gun to revolve horizontally under recoil. Follow up shots are difficult and re-gripping the gun is needed after each shot.
However if you decide to proceed:
Bob's idea will save you an awful lot of work! For one thing, rd butting the standard grip frame requires welding to get any real rd butt shape. OM ally grip frames pose another issue.
For shape considerations at least consider the Ruger Birdshead. If you know someone that has one, trace one of the grips and overlay on your standard grip frame.
The only birdshead I like at all is the original Colt Model 1877 DA Lightning shape that Cimmarron produces, but only on a .22.
Here's a single six I converted. If you're interested I can share details on how I did it since the Cimmarron will not bolt up to a Ruger main frame. The grip frame has not been fitted to the grips yet: