Those would be good for a SS engine (318?). The NHRA spec for the 302 and 308 ports are the same for both heads (160cc on the intake if I remember right). They won't be legal for Stock though. I have to stick with the 1.78"/1.50" plus some tolerance (I think it is +.005"/-.015"). NHRA has opened up the valve job to "any valve job". I've tried to get a ruling on that, but nothing. I assume that means up to the guide now. If I could figure out how to do the valve job all the way to the intake face, those heads might be legal for stock.