Anything can be done with enough time and money; question is, would it be worth the time and expense?
The issues I can think of from the top of my head are:
-Might need a new PCM (ECU) programmed for the newer 8-speed, or need to unlock your PCM so it can be tuned for the 8-speed. The JL/JLU 3.6 Pentastar engines are not identical to the JK/JKU, particularly regarding ESS, E-Torque, and PCM setups.
-Support cross-member for JK/JKU was never designed for the 8-speed. You may need to do some cutting/grinding/welding.
-Transfer Case may not be a direct fit for the 8-speed, so you may need an adapter or just source another transfer case.
At first glance I would say the "juice is not worth the squeeze" unless you are also doing an engine swap and said engine is calibrated for the 8-speed.
Good luck!