[brainsboy]

I have been building a 460 clevor. 4.155 x 4.250. I did quite a bit of research comparing CHI and AFD. CHI is definitely the way to go. CHI listed the heads as 3V simply because it doesn't work with stock intakes. The intake ports were raised as you can see in the photo below, and it requires a CHI 3V intake which is around 550-600$. The heads also have exhaust ports in different locations so if you already have a 351C you most likely have to modify your exhaust for things to work.