Righ now you probably have a 2.48 rear gear in the wagon. i put a 200R4 Buick Grand National trans in my 1979 El Camino and swichted to a 373 posi gear, but if i had it to do alover again i would have put 3.23 gears in the Elky. It went from 18MPG to 14/15MPH, but it does run 8.40's in the 1/8 with alum heads on a crate 350" motor.
JMO
Zip.