Thanks guys, most of what you mentioned I have already looked into. Do have some ideas now for my next build after this one. Keeping this one on the cheep side with the CZ 550 action.

My 460 Weatherby is my only comparison point that is at all close. It will be a bit of a jump to the 600 Overkill even at a starting load. I'm not too worried though. It's less of a jump than going from my anemic 338 Win Mag to the Weatherby (30 ft-lbs to 115 ft-lbs).

460 Weatherby
500 grain bullet
2700 fps
9.5 lb rifle
115 ft-lb of recoil energy

600 Overkill
900 grain bullet
2300 fps
8 lb rifle
300 ft-lb of recoil energy

2100 fps
250 ft-lb of recoil energy

1800 fps
200 ft-lb of recoil energy