76 C-body as daily driver

I think that with a Thermoquad, some 2.76 gears and maybe a little "custom tuning" <-----cranking up the initial timing* and disconnect the EGR.....it might not be too horrendous o' mileage. Betchya could maybe even beat 15 on a steady-state freeway cruise at 55 MPH. In high school, I had a '67 Pontiac Grand Prix with the GTO 400/Carter AFB. I disconnected the accelerator pump, cranked up the initial timing and installed a vacuum gauge to look at while taking off from a green light. Anyway, I think I got almost 21 MPG.