The .308 and 7-08 are both good choices. I don't know how far your normal shots are for hunting....if in fact you do hunt, but I shoot a 14" 7-30 Waters barrel from the Contender frame. I tell ya, the recoil is like a small puppy and the accuracy is nothing short of fantastic. Since your already shooting the 30-30, you have the brass to fire form for the 7-30. You just need the dies.
Once you have the 7-30 brass fire formed, it will no longer chamber in the 30-30. However, I honestly can't answer if a 30-30 cartridge will chamber in a 7-30 barrel. My guess is no...but I would need to check the OAL of the 30-30. But I'm sure someone will jump in here with that info.
Anyway, my longest kill shot with the 7-30 was 130 yards.....on a groundhog!!! Right through the shoulders....right where I aimed......scoped barrel of course.....and resting off a tripod. But....one dead groundhog. And one smiling hunter!!!
Dave