I thought 2.9L engines from 89's on had corrected the head casting issue.
Not really.

The newer heads were somewhat better, but still had the cracking issue. And never expect an 89+ to have the upgraded heads by year, there are things to look for. World Prod heads are even better.
The OP is right though, you can get a better running motor (performance wise) for cheaper trying to adapt a carb as opposed to going with a MAF computer and trying to tweak it. Or even more headache - an aftermarket engine management system.

I'd never consider the SD/MAP computer with anything performance.
Look in the tech article forum on this site, there is a guy who adapted a duraspark box on the engine. There is a book on 4.0,2.9,2.8,2.6 OHV V6 engines that states that a 2.8L dizzy can be made to work in the 2.9L with the appropriate gear from the dealership (didn't give part #s though). I have no clue on that, it's been brought up, but no one has tried it that I know of. I have no idea if the stock could be made to work, or if there would be some way to use the pick up (or modify it?) to be used with a duraspark box (or maybe even some sort of aftermarket ignition module?).
For putting on a carb, you'll simply need to make an adapter plate for one. I thought about this and came up with a 2 piece design at one time a long time ago. The hard part would be keeping the ports to the lower from the carb equal (like keeping the 2 middle cylinders from being richer than the 4 others). My brother has a mill, so it would have been feasible for me to do. There's no manufactured intake for the use of a carb on a 2.9L.
All in all, no one really tries to do what you're goal is, I would like to see it work myself. It's going to be an experiment for sure. I've modded mine with using the EFI system, it was pretty quick for what it was, but decided a V8 would suit me better.
Pete