Rebuilding a 74 Duster - Kinda...

So my first car was a '74 Duster with a /6. I drove it for many years and then I rebuilt the engine and transmission but never put it back in as I was missing a torque converter. It had been sitting in a field for the last ~6 years because I never had time or money to do anything with it. I now have plenty of both so I have a simple question...

If money was not a concern - what engine would you put in it?

I'm currently looking between a 225, 318, 340 or a 360. (Bonus: How exactly would you build it?)

Things I care about:
Power.
Beating my friends 351 Cleavland on a strip.
Street-ability (decent MPG, runs smooth, sounds bad-***)
Reliability
Finding replacement parts

Things I don't care much about:
Numbers matching.

The car is currently at a shop getting all the much needed bodywork done. It was recently media blasted but here are some pictures of the car if you care to look.

http://photobucket.com/DuckensDuster