I'm rebuilding a 390 for a 1967 Fastback. I am putting new pistons for sure and a new cam. The engine was originally a 2-barrel but my dad changed it to a 4-barrel intake but it still has 2-barrel heads. I need some ideas to make the engine to where it would efficently but also have some good power?

 

if you have loads of time you might just port the existing heads for a bit more fun

 

Find the FE forum and talk to the guys there.

http://www.network54.com/Forum/74182/

There are a lot of geat guys on the FE forum, but I'd also talk to Barry Robotnick (not sure of the spelling) on the FE forum as well.