Why not the 7.62X39? I have a buddy is Florida that hunts with his Mini-30. The deer he shoots are just as dead as the deer shot with a .300 WM. It's performance is almost equal to the .30-30, which ain't bad. I use the Marlin 336SS in .30-30. If it were possible to make a 336 in 7.62X39, which it is not because of the tubular magazine, I'd think about buying it because 7.62X39 ammo is cheaper to plink with, and it's performance is similar.
As for the FMJ HP, I think SP is probably the better choice. I don't think you'll get the expansion with any FMJ type round. For hunting, use the Remington Core-Lokt SP.