Rather than 7mm or .270.... you should go with the B-29... it's a bad azz round. Had a write-up on it a couple years ago in Rifle magazine. You may ask Mule Deer.... he was one of the guys who created the cartridge.
Not a lot of info out on it.... but ask around here and you may be able to find some stuff out. I think it would be exactly what you're looking for.....
