I'm thinking of building a 400M propane motor for my 77 F150 but I'm looking for a website to answer some of my questions. Basically I want to use ported heads, a Comp 268 cam kit, Edelbrock RPM intake and headers. What I want to know is what the proper compression would be and if the cam is suitable. I want to save money by running a cheaper fuel but hopefully still make around 400HP-450LBS/FT. Or am I just dreaming?