Thanks to you guys, this thread is really interesting indeed. Informative too.

David I forgot about the Nifty Fifty ad and the "plus" model. I found an article online where an owner of one said he got upper 40 mpg's in the mountains with one, and as much as 56 mpg on a highway trip when he was really driving for best mileage!

You're right. I should be aiming at 60 or 65 mpg!

This will be a fun project, but to be honest things like fuel injection or lpg conversions are out of the question for me. I will focus on maximizing the standard equipment pretty much. I will use my '76 A14 short block, with a set of A15 [basically flat top] pistons for best compression. I'll stay with the standard cam and use the '80 A14 small round port 990 head on it. I do have a wide band oxygen sensor setup on the car and will be able to jet the carb for max efficiency. The car does have a Pacesetter header on it and a mandrel bent 2" exhaust system with a low restriction muffler. They will stay of course, but as noted really aren't needed for the low engine speeds I will be using.