You can fit the 38"s on with a 3" body lift and massive guard trimming. Of course you have to run the widest offset rims you can find or wheel spacers.
I have seen a Gen 1 swb with 38" Groundhawgs and it didn't foul on anything.
The fitment is definitely do-able.
The problem is power and gears.
The Gen 1 I saw had a GM V8 and could turn them ok.
The other issue is axles even the mighty 33.5mm 3.5 V6 units would be out of their depth with any serious.
wheelin.
The IFS would be definitely way out of it's depth with a tyre of that much weight. You would grenade stuff on the first obstacle IMHO.
However I do know a guy who ran 36" Swampers on a Gen 1 swb V6 for many years without too many CV breakages and only one rear axle failure.
But he could drive really well.