[My427stang]

Watch calling the D2/C8 heads with the med riser port location "med risers" they are actually 390 GT heads with an exhaust port for the Fairlane.Mustang body

Not even counting the exhaust bolt pattern options, they are very different heads all together and the intake port is hardly a med riser in flow potential, although located in the same place, they are narrower, have different valve spacing, the exhaust port is completely different and the chamber is completely different (Although the chamber is actually real detonation resistant with lots of quench pad and an almost kidney bean shape compared to any other FE)

Matter of fact, if you look at the exhaust port on a C8/D2 head, you'd be amazed at the valve bowl, I have no idea how they can even run on a 390, the seat to bowl transition is horrible, like 60% of the seat area

C8 / D2 have a good modern chamber, but need a LOT of work to make big power. Great torque head if you have a header combo that will match, but a standard FE header will not seal against the head