I know you're against "custom mods"... but I would not hesitate to dump the H3 radiator entirely and adapt a pre-engineered intercooler/radiator combo (from some other application). After all....no need to build a custom intercooler to run a custom radiator and do custom mods to your H3....when you can buy a package like Patterson's Jeep and save a bunch of headaches. Just open the box...drop the combo down between the condenser and the motor...and mod the truck as required. I think the performance and cost of a pre-engineered unit would smoke anything you could come up with (even though it won't look "factory").
I will be up there today, and I will get some info on his setup.