what will 906 heads with 2.14 intake and 1.81 exhaust valves, and the mopar performance porting template modifications do in a stock compression 63 413? i also can get a stock 375 horse magnum cam (new) with a three bolt double-row timing set to also install in the 413. the motor is out of 63 chrysler 300 2 door and has been rebuilt prior to me getting it. it runs really well with the stock heads/cam/intake. i plan for an Edelbrock RPM manifold and it will have a 3.55 or 3.91 sure-grip. i have a holley street avenger 75 double pumper and 1 & 3/4 inch headders with 2.5 dual exhaust, flowmasters and crossover tube for exhaust. it is all in a 71 shortbed truck that i am converting from street to mild bracket racing duty. just curious to know what the compression would be, stock 413 heads on motor, and then with the 906s on the stock 413. what do you think the 375 hp cam would be like in the 906 combination? thanks, JP in KS.