[elhigh]

You have nothing to defend from me. Keeping old iron running is a different, but just as relevant, kind of economizing. I mean, look at me: I have an old tractor because it's fun. I could have bought a boat, but you can't plow snow off the driveway with a boat.

If they're as old as all that, you probably don't want to make many mods to those either, though you could consider removing the original induction systems completely and replacing with appropriate Megasquirt or applicable TBI systems. You should be able to squeeze a few extra MPG out of them while retaining the capacity to return them to stock configuration in an afternoon.

The returning to stock would take an afternoon. Sorting out an all-new EFI for the initial mod would take considerably longer.