i have read about tbird guys putting in a E303 cam. is it pretty risky to do with the valves. i know every engine is different and all but how much clearance would a E303 cam give for the valves?
I going to say you probably need Mustang pistons because they have valve reliefs. The only heads that might work are the Twisted Wedge heads by Trick Flow. I think that TurboCoupe50 runs those heads on a stock flat top short block with a big cam. The only way you'll be sure is to measure piston to valve clearance.
You need mass air,If it cleares without a gasket on the head turning
by "hand" you should be ok,It's close I checked it,You could go with a little less and not risk it.High r's. shiznit streches.
E-303 will work with TF Twisted Wedge heads & flat top pistons. Their spec sheet says: Maximum camshaft lift with factory flat top pistons: .540" lift
You will need to go mass air, like kitzdnm said.