428 CJ heads were similiar to medium riser 427 heads and they are about 150 cc. The thing is that 150 cc may sound small if you compare that to small block aftermarket heads, but the FE head port is shorter...about 4 inches compared to 5 inches. The manifold runner was of course longer on a FE. Saying that, 150 cc FE would be like having 188 cc for a small block head. Edelbrock aluminum FE heads are around 170 cc or like having about 212 cc for a small block head (aren't Edelbrocks modeled after the high riser head?). Hope that helps and ignore the small block comparison if that wasn't of any concern.