the great thing about it being a racecar is that you dont need the power valve. i would take it out all together and put a plug in. get it all done with the jets. that way it cant leave you hanging and melt down your engine if it doesnt open for some reason. 76 primary and 86 secondary jetting worked well for me before i figured out the power valve thing. should be a good starting point for double digit psi and a 650 carb.