Originally Posted by Dragonoake
Basically, you want a high velocity engine with lots of bottom end torque to get that weight moving.
Back in the 80's, "Super Chevy Magazine" had the "Econperformer" project going where a 4100 pound '70 Monte Carlo with a 350 (Crower Baja cam, SP2P intake, and a leaned out Q-Jet), a TH-400, and 3.31 gears was running low 14's@95 mph and getting 25 mpg
And that was with 80's technology; I suspect you could do better applying the same ideas with Vortec heads, a 700-R4, and TPI
vortec heads and tpi is an expensive combination , the vortec tpi base will run u around 600$'s just for the manifold base , by the time u pay for heads and intake etc i would just do an lsx and t56
for the ultimate budget i would do a stockish tpi engine out of a camaro or vette, they can be found cheap for comeplete good engines, hell i just sold a complete 40k mile ( original not rebuilt) l98 and 700r4 combo for 300 bucks
tpi is just that lots of bottom end and falls off fast in the upper midrange