I gotta '66 model with a 292 and overdrive. I get about 13-14 mpg on average. I'd probably do better if I stepped down the primaries on my 4 barrel one stage and dropped the float a little.
Woogeroo has pretty much covered it all in his "buyers' guide" section as to what to look out for. Be
sure to check
all electrical stuff before you take off. Last thing you want to do is find out you have no headlights when yo got an hour left in your trip and the sun just went down!!!
-ftyler