I wouldn’t want to open up the bolt face. If you did you’d probably need to mess with feed lips or something too.
I wouldn’t want to chamber a short action cartridge in a long action. No reason other than you still have a long bolt throw but not the extra velocity.
If you were set on a 6.5 and willing to consider a wildcat a 6.5-06 would work. Otherwise either a 6.5x55 or 6.5-284 are good choices.
If you are willing to consider other calibers you could open up the choice quite a bit. 280, 270 W, 30-06, 338-06, 35 Whelen, the list goes on.
I would probably go 30-06, but I love the 30-06. Take that with a grain of salt.
