So now that my stock lt1 heads are ported which header gasket will match up the best? I have looked at felpro 1405 and 1406's and they dont seem to match up very well. Can they be cut or is there another part # that will match up better? My exhaust ports are square now instead of d shaped so the 1406 is out unless they can be cut and the 1405 is not even close, it's blocking a good bit of the ports across the bottom edges. Please help...