Finally investigated why my Fiance's old 2001 WJ 4.0 quit last winter. Turns out it looks like it has the dreaded early "0331" cracked head at about 180K miles. I've found a 2002 4.0 from a TJ Wrangler. Fella is converting to diesel for his crawler and doesn't need the stock engine anymore. Do Wrangler and GC use the same 4.0 engine block in '01 & '02? So I could swap the 2002 Wrangler 4.0 into the 2001 GC directly? The '02 engine would get me the updated head, so the crack won't happen again.

Then my other choice. For about the same money ($700), I could buy a used '02-04 head + a light rebuild on the stock '01 short block. Lots of labor for me, but I'd know what I have when I'm done. If the short block is hurt (beyond bearings), this bet would be off because the cost would escalate.
Or, just swap in the complete Wrangler engine (100k miles) for the same $700 and hope for the best, quicker and less labor intensive. Either engine would get a new oil pump, front and rear seals and core plugs while the engine is out. Your thoughts?