I am a huge 350 G&H nut too. I own an original Western round, and it is my talisman against vampires and IRS agents. I intend to build a rifle for it, possibly on a sporterized P17 Enfield action just because you never see those any more and there were some really sexy sporters built on that action back in the day. To me, the 350 G&H is the ultimate American big game round. I probably give it far more credit than it deserves, but I can't imagine anything nicer. Developed by Americans, with an good American name (based on a British case...but we don't need to mention that!)

The original loading was, in the references I've found, .357, not .358. The round I own has a sloping shape to the bullet which makes it difficult to mike, and it doesn't matter anyway, but I thought I'd throw that out. When I get reamers and dies made I'll use the .358 dimension.

I suppose you send the cartridge (carefully) to a tool maker like Clymer's, who will make the reamers for you (one for the chamber, another for the reloading dies) and then have dies made, and then have a barrel short chambered, and go from there? Seems a logical process. Am I leaving anything out?