You could probably build a Cherokee--even a 94--and GREEN no less--or ANY rig--into a monster that'll do anything, maybe even crush an 80. But by then do you really have a Cherokee? Or a Cherokee body on top of some incredible gear and creative fabrication? Just sayin.
The 97+ Cherokee is a completely different vehicle. It had modern electrical wiring, and what you might consider "modern" production. Was something like 40% stiffer in unibody construction than the previous models. IMO, if you really want one, you would be insane to buy anything pre '97.
Everything up to 1996 was designed starting in the late '70's. Seriously long production run.
Swapping axles does not swap the vehicle. If I put a set of Prorock 60's under my 80, would it still be an 80? Of course. Swapping axles is far less than say taking an FJ80 and swapping the engine, which is something poor underpowered Toyota loyalists have been doing for years.
This XJ has the stock rear leaf spring suspension plus traction bar (anti-spring wrap) with a simple conversion of a 4 link front to a mid-length arm 3 link with lower arms mounted on the plane of the axle tube to keep angles good on a 6" lift. It is on 37's, D44 front/D60 rear. We have 80's here that have gone to portals or other upgraded axles in order to hit harder trails, what is the difference? We also have chop topped 80's here.
You can see the huge difference in underbody clearance between an XJ and an 80 - 6" of lift on one of these is simple to do, because of the stability of the rear leaf suspension. No engineering required. I know this rig runs the Hammers and other BOTW (Best of the West) trails and has been doing it for years, fully utilizing 12" of shock travel on all four corners without having compromised suspension geometry and balance.
Toyota owners tend to be so biased to Toyota components that they spend a ton of money keeping Toyota running gear under their rigs, doing things like turning 80 series rear axles into front axles running on the weak side of the ring gear. And then of course blowing them up.
Which is why I have spent more time with busted Toyotas on the trail in four years than I did in 8 years running mostly with Jeeps, on the same trails, and these are the big things like busted t-cases and blown R&P's. Sometimes it is better to know your weaknesses and fix them instead of believing you don't have any.