What is wrong with this combo

You aren't running a two-step? You should.

Leaving with the throttle blades all the way open is worth ET. Plus you don't have to worry about the transitional parts (squirters, etc) causing problems.

Also, launch RPMs seem pretty low for a stick car.

Did you degree the cam or "dot to dot" it?

I agree with these guys that the valve train should be checked. Make sure the springs are tested, and that none of them are messed up.

Definitely do a leakdown on the motor also.

Clutch slipping on the top end?