A true 9.00-1 with some keith black(or cast for that matter)pistons would work well with a short duration cam like a xe256/262 or similar grind.
small diameter long tube headers,dual plane intake with a t-quad or spread bore holley 650 vac secondary(or a well tuned 600 eddie),and a well curved distributor with vacuum advance.

Any improvements to the head flow will return better efficiency for mpg and performance.

A tight low stall converter (maybe a towing vert?)and some 2.76 gears will net you a nice highway mpg.