The best factory head that never was

Specifically the j head intake port, 974 non drilled exh port, in two versions...one open and one closed.

I love the 308 exh port too, just its cast really thin and tight between the roof/guide and floor.
If the 318 exhaust port was cast into a 360 exh port in such a way that you could literally grind it to be as big as a 360 exh port 'not that you'd need to open it up that big' damn...that would be the ticket, plenty of exh floor without the roof pinching it off.

Fyi to those who don't know, the intake short turn of an x head has a longer plain, more of a flat peak