A lot of times not much thought process goes into what all it takes to actually do one. Just like some have said they'll do it in a weekend or so.
Years ago before computers, electric doo-dads it was simpler, so much so.
I mean we've built VW bugs on CJ frames, SBC in behind the front seat in a Corvair with tube frame, Firebird on a Blazer frame, big block 32 Fords, lifted Dodge vans and ran 40s on them. Lots of crazy things back in the 70s, early 80s
But the KJ takes a bit more planning , more to swap, more to change than just pulling the 3.7 out and installing a ________ in it
Then you also have to think suspension, transmission, transfer case, front and rear diffs , wiring , exhaust, all of that takes not only mechanical skills and knowledge but some imagination .
Some of the ones that have been tried, booger welds would of been better than what they were trying to use.
So a lot of things to plan and lots of experience and knowledge needed for sure. I think most think its a drop in and go , well until they get the old out, the new started to drop in and then its " Oh crap " now what.