Is it worth it?

As a fan of the slant 6 I have been thinking of converting to the super 6 set up. The parts are hard to find. I think I just need intake manifold 2bbl carb, throttle, and kick down linkage. Not sure if I need anything else. If I am able to do this what should I expect in performance?, gas mileage?
What year cars should I e looking for with this set up to get parts? Thanks!