You're talking about what they call a "Clevor". Here's some good reading:
http://www.mustangandfords.com/techarticles/30220/
But like everyone else has said, Canfield/AFR/Trick Flow will way out perform them.
This whole Clevor concept started back before the aftermarket was so expanse. Basically a cheap upgrade with parts you can find in a junkyard (back then). Neato nifty stuff, but the money can be spent elsewhere more wisely now-a-days. We're attempting to build a 393 with the same junkyard mentality, just to see if we can do it. Believe it or not, the only thing we're gonna have to "buy" aftermarket is the crank!
