Take a look at 250-260 duration camshafts you'll get what you desire. I can't tell you lift since I don't know your clearances between valve & pistons..youll need a torque converter too
The old Mopar 0.528 solid will pull past 6000 rpm and it is only 236@050. I don't think I'd go much bigger than that for what the OP is describing. Kind of depends on some other factors which he hasn't mentioned but too big of a cam will make things much worse than too small.
