MPG build 360

I should of went with a stock 1968 318 grind or stuck with the stock 360 cam
for straight fuel economy and low-end torque, probably best. My main thrust in the previous post was to get you to understand that a low cruise-rpm is not always the best Idea.
I once ran a 270/276/110 Hughes cammed 367 with a final-drive of 1.97 (manual-trans,overdrive) and had fabulous results at 85=2100, but with the timing cranked to 56 to 60*. That cam, by ithe math had 53* of overlap! but the alloy headed engine cranked over 185psi pressure. So, I know fuel mileage can be had with that type of cam.
As is so often the case, combo is everything.
Now;
If your engine is already assembled;
How much is a new cam and lifters gonna cost with gaskets and such?
Compare that to a theoretical 2 mpg increase.
And then figure out how long it will take to break even, with the number of miles you typically drive in a year.
Many times it's just not worth it to make the change.
Furthermore;
if the engine is already built, I highly recommend to not worry about it at this time, just drive it.
Get the timing bugged out, and the cruise circuit leaned out, then do some mileage runs at different rpms; and figure out the sweetspot rpm, and badaboom, yur done.