/6 single or dual exhaust?

you can bore the original exhaust manifold to 2 1/4 inches and run a 2 1/4 in pipe (single) all the way back. Simple and lighter, and cheaper and more than adequate. Super six well tuned will yield 20 mpg city and 25 highway (well at least mine does) Electronic ignition helps too along with a well curved distributor and some advanced timing