Usually in the classics, want to put a mod in my 67 Fastback. But the small amount of displacment always bothered me. I want to know if the 5.4s can take the 4.6 dohc heads. As well as what is the largest amount that the 5.4 can be bored/stroked to. Was going to put a 390FE but because of weight and the fact that I am merging technologies I wanted the mod. Is all I have a pipe dream, or can it be reality without Bill Gates checkbook?