Slant 6 MPG Upgrades?

Some thoughts, as others may have mentioned and some of which you've noted:

- With the cost of aftermarket EFI and all the mods you will have to make, it will take you a loooong time to pay it back in fuel savings. If you're doing it largely for the fun of working on the car, then I can support that 100%.
- You will get better fuel economy with a later slant that has the cast crank. The cast cranks are something like 15 lbs lighter, which is a huge difference in rotating mass.
- Highly recommended you figure out that electric fan situation. On my old warmed up 318 getting rid of the fixed fan was worth around 1.5 mpg on the highway (at 70+ MPH). I had a 3.23 gear with a 26" tire, so about the same RPMs you're looking at.
- Look for a 2.76 rear gear. Will be the biggest bang for the buck fuel savings, and with a 7¼ rear you should be able to get the gears super cheap (or even free) from someone here.
- Don't discount the value of synthetic oil and differential fluid. Trans fluid probably helps too, but I'm not sure if it's a lot.