318 MAX fuel economy builds?

mgoblue9798 said
Going against the grain here, but if mileage is the primary concern it is hard to beat the lean burn set up.

If it is still working after all these years I would leave it. It leans AFR out at part throttle cruise to 17 or 18 to 1. Exactly what is needed for best mileage.

In my case the lean burn is going away. The last 2 years I had the car out (fair weather cruiser) it started pinging randomly at weird times (not when you'd expect with over advanced base timing) and quite intermittently at that. I have everything to convert to the 4 pin ecu, but the more I hear about it the more I'm considering trying an HEI setup instead.
I have had many 318s over the years.
On another one I had, an 83 d250 I went inside the engine and put in a stock replacement cam for a 360-2 barrel, a set of EQ heads (converted to a magnum drivetrain) added a performer intake (original performer, not air gap or RPM versions) and a Carter afb 625 and I was quite amazed at how much better that engine ran plus a quite noticeable improvement in mpg (wasn't my main goal in the cam and 2 bbl-4 bbl swap but I wasn't complaining)
I plan on doing exactly the same thing on the 318 in my fury that still currently has it's lean burn. I have all the parts here for it. My "cam of choice" happens to be a Melling SPD 25. The only difference in this case is that instead of the EQ heads like I put on the hay truck, I have a fresh from the machine shop set of '302s sitting here for that engine's upgrades.
All that remains before the parts are swapped is to get inside those '302s with a die grinder and a set of burr bits while hoping I don't "oops" the fresh valve job.