Alum Heads

I think it’s a load of ****. As cast for a teen should be able to carry you very far in performance. A CNC’d set just raises the bar higher. I don’t see a problem anywhere with a set CNC ported on ether engine.

It would have to be a disastrous mismatch to be bad. IMO of course.
Well wouldn’t a cnc head be a disastrous mismatch on a basically stock 340/360?