21 mpg?!?

I'm gonna try this recipe-

74 Duster +- 3200 pounds

318 with 302 or magnum heads 9.2-9.6 CR

Comp 256 cam, air gap, 1-3/4 headers, 3" exhaust

3.73:1 B body 8.75

833 o/d manual

I bet it does great in the useable street power RPM range and still good on the highway, plus turn a decent 1/8 mile time.