Timing set swap or not?

I'm swapping out the engine in my 2000 xj. The donor engine has only 90k on it but the timing chain has a lot of play(I think at least 3/4") sided to side. The blown up engine has 190k but the timing chain and gears look in good shape. Is it crazy to swap the timing set from the blown engine to the donor engine? The donor engine is from a 90 Comanche, and I'm only using the block and rotating assembly.

If it fits, it fits. Often while down in and around there, my first inclination is to always replace with new OEM parts if possible. Same for oil pump, etc., while I am there, I might as well change it out, and then have useful spare parts as back ups. I usually carry an extra fuel pump, oil pump, water pump, thermostat, starter motor, cap/rotor, and have been known to carry a complete dist. system in it's entirety. Hate being in the middle of nowhere without an easy exchange on the spot. Specifically, I cannot say it the measurements of the two different years mentioned are duplicates. Others will tell you. In other past times, OEM Jeep timing gear/chain/sprokets had one of those parts, sproket to the cam if I recall, with metal/nylon, or something. Often aftermarket sources could provide solid metal setup which would not wear out as fast as the aforementioned. I have yet to look at my mechanical timing setup on my almost now brand new '89, lol. TRAILS!

Turns out the cam gear has changed at some point. The earlier style has a spring inside the cam gear bolt that keeps the cam in the right spot, and the later style has a retainer behind the cam gear that bolts into the block. Naturally the older style block doesn't have anywhere to bolt this cam retainer to. The threads are different between the two cam gear bolts and the cam snouts are different as well.
This is interesting as I'd heard that the cams had only changed in profile, but that they were interchangeable. As far as I can see, you can't interchange cams between these two different 4.0 block castings, and you can't interchange timing sets either.
I was ready to swap cams to get the newer design lobe profile, and be able to use the timing set since it had very little play, but looks like the difference in the blocks won't allow it. Anyone know a way around this?