There are several ways to "cheat" so to speak.
A blaser bolt gun, a TC encore or contender or a Mossburg SSI (if it was still being made),AR lower or longer frame AR style lower with different uppers.
But really there is nothing in the world you can't hunt with a .280 remington or a 7x57mauser.
As for what 6 long guns I would keep/aquire not "cheating"
mossberg 835...just for the great patterns.
Reminton 1187...12ga for doves/wingshooting.
Winchester model 70 .270 win.
AR in .223/5.56nato
Tc Omega .50 cal Muzzleloader