One question is how much would you drive it? Only to shows and not very far away, weekends, semi-daily, daily, over night/weekend trips out of town, short road trips or full blown road trips?
Could be a great road trip car with a mildly build up 6 for a little more power and a 5 speed, and I think you could get near 30mpg on road trips.
I'm basing that number on 2 things. I had a '66 with a stock rebuilt 6, C4, 2.83 gears and got 27mpg.
We just did a long road trip(post on that coming soon) in our stock '65 GTFB with an un-rebuilt 289 4v, T10 and 3.00 gears and got a best of 23.5mpg.
'68 J code coupe back in H.S.1st car. Now 65 GTFB
Daughter & I built her a '66 coupe feature car in 8/04 MM & '05 Meguiar's winner see it @ Meguiars.com Made matching pedal car for her daughters.
Built a '68 j code coupe with oldest son. Made matching pedal car for his sons.
Built a '67 FB with youngest son. Yes I'll be making a matching pedal car when he has kids.
Future '74 TR6 Project for Wife