318 MAX fuel economy builds?

I have a fresh set of '302 heads that need a little cleanup work (surprisingly they need more cleanup in areas that have nothing to do with how the engine runs like where the oil runs and drains back to the crankcase) and a set of '714 heads here that are "as removed" from the donor engine which was some kind of a reman engine as evidenced by the heat tabs glued onto the ends
Yup, I always debur my engines and parts for that reason. The 920 heads I bowl ported last year and are on my Cudas 273 were surprisingly clean ports compared to the BB heads I've ported from the 60's and 70's. I just did a light clean up in the bowl, back cut the valves and gasket matched the intake side. My car has a 904 with 2.94 gears and my carb was way too rich and it gets just over 15 mpg with the 275-60-15 rear tires on it turning about 2500 at 65 mph. It's not fast and the mileage isn't great. I think I can get this 360 to get over 20 and have some power when needed. I'm hoping anyway.