Sellier & Bellot offers 7x65R ammo and dies are still available from Hornady.

I believe you may be able to use 7x64 dies with a .303 shellholder. I used 7x57 dies with a .303 shellholder {same sh as the .375 H&H} with my 7x57R.

Who is the Idaho fellow? I am looking for a combination gun, trying to find a source for them.