Originally Posted by chevelledave

your better off going with a good AMERICAN Head ...AFR .DART, EDELBROCK...they may cost a little more ...but in the long run they will save you money over the CHINESE JUNK...If all you have is a block ...the crank rods and pistons are gonna be the same price wether its a 4" or a 4.250 stroke ...rods are gonna be 6.385 in length ,,with a pin height of 1.270...piston should be readily available in .040 over ...Also do not rule out the GM factory 781 oval port casting if your on a budget ...easily found and will make tons of power right up to 6000 tp 6500 RPM...check Eagle and Scat for a KIT ...you can get them balanced and ready to go ..

Originally Posted by cambirdracing

Oval port for low rpm torque, rect port for high rpm h.p.

Originally Posted by dkcoleman01

ok is it best to go with oval port