i need help w/duster engine

Don't take the heads off, clay is NOT an accurate measurement. Checking springs and a dial indicator are the only truely accurate method but 100*? Not necessary use my numbers they came from Engle cams and I have a much more radical cam than the roller you are looking at.

The long valves are because the stock A valve installed height is only 1.65". This is not enough to allow for the stiff valve springs (think thicker coils and triple springs) that are needed for the roller cam to function properly. Any spring strong enough to handle the roller will be coil bound at .600 lift if it's installed at 1.65". This is basic physics, two pieces of matter can not occupy the same space at the same time.

If you want to improve the ET of your car I can recommend several things to do, the first would be better heads, and by that I don't mean Edelbrocks. Indy's, W5's, B1BA brodix, W2's, large port Commandos, etc., there are a bunch out there before you get into exotics like the W8 or W9.

Head flow is where the horsepower is. The more air and fuel you can pump through the motor the more power it will make. That's why larger cubic inch engines make more power, they can pump more.