Thanks for the positive support! There is a person on The Diesel Place who did a 6.2L conversion to a Roadmaster wagon and it was doing over 40 MPG Imp. Which would be about 35 MPG US. The main issues are time and funds. Both are limited. I am going to "fuel" around with fuel pressure and injectors first. I'd like to also get involved with burning chips if I can source the equipment cheap enough. I think with better fuel atomization, more EGR, and a more aggressive spark table I could squeak 30 out of it. If you look into the history of the TBI engines you find that the last 2 years they were produced, The TBI 350 in the trucks used smaller injectors and higher fuel pressures. That was a stop gap measure to pull the TBI trucks through the tougher emissions regulations unt they went with the VORTEC CFI unit in 1997. GM never came out and said it, but what other practical reason was there for the sudden change during the engine's twilight years?
Also for anyone with one of these engines, the single wire O2 sensors don't last too long. They are cheap so don't skimp. When you change plugs, change O2 sensors too. You can't trust them once they hit 30,000 miles. For $25.00 why take chances?
If you think about it, the LO3 has the architecture for a fantastic fuel economy engine. The small ports, with the high swirl chambers, the smaller bore with less chance of fuel condensation on the walls, the long stroke for good low rpm torque... The much maligned 305 is a simple, reliable and adequate V8 for family cars. It is capable of good fuel efficiency and adequate performance. The reasons it is perfect for this assignment are the same reasons hot rodders throw them away in their quest for performance. I will keep you posted on the mods as they happen. In my quest to "improve and modify" myself I am trying to commute by bicycle a few days each week so I don't rack up as many miles as I used to. I suppose it would be unethical to add the 40-80 miles a week I cover by bike to my fuel economy calculations!
If I get close to or exceed 30 MPG I will leave the car alone except for maintenance. I won't bother with a diesel conversion for 5 mpg. With the price difference between regular gas and diesel fuel, I would never see the payoff.
Also another thing on the maintenance list is a timing chain and gears. The factory ones get sloppy at about 100,000 miles and I am at 101,000 now. So probably in the spring, that will get done.