This is a ton of great information. I don't mind reading a long post, but to
@rumblefish360's point, proper paragraphs are key for me.
The one thing I think most guys don't consider enough with fuel economy is the bit about parasitic losses. Over the years I have put some thought into efficiency for power and fuel economy, but never considered casting flash in the oil and coolant passages. That's definitely not nothing.
Here are a couple more things to consider, not necessarily directly related to the engine:
Electric fan. I know some guys hate them, but in 20+ years the electric fan I've had on my car has done the job and I'm sure saved a ton of fuel.
Synthetic fluids everywhere at the lowest viscosity you can get away with. I won't open the can of worms on engine oil, but the ATF+4 is a good choice for efficiency in an automatic transmission. And a synthetic 75w-90 gear oil for the differential will also help. Even synthetic wheel bearing grease might do something, if only a little bit.
Also, 4 wheel drum brakes are probably better than older disc brakes. Many old disc brake setups tended to have a slight bit of contact between the pads and rotors all the time.
Finally, an air dam at the front of the car. Not just a chin spoiler, but a dam that curves around to keep oncoming air off the front tires. The 91 Ford Ranger piece seems to work well on A bodies. You can search this site for examples of guys doing it.
