my advice is a good strong 350 with a rv cam and maybe a expertly built q-jet and a recurve hei. run the 700 r4 with maybe a 3.70 or 3.55 gear. whenpulling the load run in drive not overdrive. it will kill the mileage but save the tranny. and as always let it breath well. long tube headers with free flowing exhaust and a good fresh air intake system. i would bet once tuned right it will run in the 20's. i ran this setup with out the headers and fresh air system in my 82 chevy and got 18-19 consistently. so with the extras i would add a few more mpg.
