It's an interesting question, though. Dealing with the ignition system alone*, if you install a distributor exactly 180 degrees off (which would be at the TDC mark on the crank, but TDC for cylinder #6 instead of #1 in the case of the 4.0) it will work as long as you also then install the plug wires 180 degrees off. I've done this on other vehicles, and unless the distributor has some odd asymmetrical firing pattern, like an early 90 degree V6, or some VW's and old Porsches (some of which a slight timing variation between the two banks), the engine doesn't know the difference. It's the spaces in between that don't work.
Remember that the timing of the spark itself is only one function of the distributor. It must also send it to the plugs via the rotor, and that timing is fixed entirely by distributor position. Beyond a certain range, it just won't line up. In addition, the range of compensation the computer can provide is limited. I'm not sure which factors came into play, but when I experimented with timing on my 87, I found that it could not work well even if the distributor was a single tooth off. It would run well one tooth advanced, but started very hard. It would start well one tooth retarded, but stalled with throttle.
*As I said, I know that this works on old carbureted engines, but all bets are off for MPI fuel injection. While the ignition system might work perfectly 180 degrees off, it probably would work very poorly on any fuel injected system which, like the Jeeps, uses something other than the distributor to time the injector pulses. If the injectors are still firing 153624 while the distributor is firing 624153, the injection pulses which are supposed to occur just before the intake valve opens will occur instead just before the power stroke. Fuel injection will always be two strokes late, and I'd expect mixture problems.
ETA looking at the question that gives rise to this thread, I would strongly advise double checking the timing, since it's quite possible the engine would run "reasonably well" with the distributor wrong, but that mileage and power would suffer.