I have a set of the ones that were produced in the 90's for stock and super stock class racers. The ports are large enough to push a coke can into and were obviously done by a head shop. W2 rockers will not work unless alignment is not important to you. Mine use a .500 offset on the intake and standard offset on the exhaust. I am using a MP pieces that is actually .450 offset but I can shim the rocker enough to get decent alignment. I will be flowing these soon to check how good they are.