Personally I love your idea and your plan.
I’ve wanted to build an old car to drive that would get acceptable mileage for some time now but time/money constraints have prevented such a project. I have a 69 Mustang I’m trying to finish up now but it is being built for anything BUT mileage.
I’ve often daydreamed about a 64-65 Falcon with a 2.0L 4 popper swapped in getting 35-40mpg. If I could pull off that feat with a wagon version that would likely be the last car I ever buy as I’d drive that thing for decades! I used to drive vintage cars almost exclusively and I loved every second of it. Gas prices drove me out of that and starting a family has slowed any kind of progress towards building/modding one to drive (though it is in the long-term plans).
As far as your plan. I think you’re on a good path. However, I don’t know if I would focus quite so heavily on weight reduction (unless you just have oodles of money to blow). I’d probably just grab the ‘low hanging fruit’ on weight reduction and work more on ideas for decreasing drag, especially aero drag. At 3100 and some change your car is already pretty light by modern standards but the aero is almost certainly a wreck. The real trick will be making it ‘slicker’ through the wind without ruining the sweet lines of a classic car. The aero, I think, will be the biggest holdup towards reaching your goal.
I for one would LOVE to read about your progress and how the project goes so keep us posted.
