what are the MPG ratings for a 71 skylark with a 350 4bbl?

i assume everything is in good working order, propper tire inflation, clean air filter, etc. change the distributor to an HEI, along with the appropriate sparkplugs, not sure if you'll be able to set the advance at speed with your '71 timing tab. if not get the tab off the donor vehicle. if this improves things(mpg), your on the right track, if not change it back, shouldn't cost to much, or just leave it and not have to deal with points/coil wire. i think you ought to average around 17 mpg, pretty heavy car though, and gas isnt being blended for carb. cars either, might be worth a try, and it wont cost you alot to do that.