Anything 255g ~ 300g @ 900 ~ 1000fps should be more than sufficient IMO.
I like 9g Unique (flaming dirt) under a 255g cast SWC or RNFP to duplicate the BP load it was designed for.
I've read Linebaugh and one day I will have him make me something in a 480 Ruger or the 475 Linebaugh with a 4 5/8" barrel and some excellent grips. His work is fine!
I don't suppose it's a problem to handload a cast 255g up to 1200fps with a nice slow powder, but I have magnums for that, so I suppose having that option makes me selective that way.