They have a tall intake port, taller than my 390 gt heads. They only have 8 bolts on the exhaust side, where my 390 gt heads have 14 bolt exhaust.I was going to use them on my 390 gt motor with a 427 2x4 intake, so the ports would match up. I have seen some with tall ports with 14 bolt exhaust. Mine does have the extra bosses that can be drilled to use my gt manifolds. Are these better heads or worse?