Just bought my son a 77 SWB with a 360 auto, carter afb, duel plane 4bbl intake, stock exhaust, stock rear with 2.73 one legger, it is a gas hog (about 10 mpg or less)...considering pulling the 360 and installing a 318. Any suggestions on a gas miserly 318 build? 2bbl/4bbl, cams, induction preference? Or....is there any way to improve the milage of this 360? Thanks