4.0 H.O into a 90 XJ
 

I know it will fit, but my question is will the wiring work or do I need the wiring out of the donor JEEP?

option A: you keep the head of the old engine and swap only lhe block, no need to change wires.
option B: you swap the whole engine and you will need ECM + harness and complete exhaust (manifold, pipes etc. )

What is the diffrents between the HO and none HO jeep motors ??

In 1991 chrysler redesigned the inner casting geometry, added some stiffeners and made a new head with higher intake ports to optimize air flow and reduce noise and vibrations. Also the exhaust was redesigned. This lead to a power gain from 177hp to 192hp that was called HO (high output).
The visible difference is in the head, exhaust and intake cannot be swapped between the two engines, but the heads are interchangeable with the blocks.
The electroncs was also completely redimensioned, new sensors, new connectors, new computer. The two systems are not compatible. The HO engine does not have a knock sensor (not very important but still) and the TPS is a single unit (same signal for ECU and TCU) against the renix double unit sensor where the outputs are two. Fuel rail is without pressure regulator on the HO engine and injectors are higher flow rate.

You can put the HO motor in and youcan run it with the Renix intake, exhaust, and distrubuter. It does run right too.

which head?

I am running the HO head with the Renix Intake, Exhaust, and Distrubuter.

You can bolt a HO motor in, you just have to you the renix intake and TB to reuse the sensors.

That is not a bolt on. You can of course adapt it, nothing is impossible.

why is not bolt on?

If you bolt a renix intake on the HO motor you are going to cover .125 inch of intake port with the manifold gasket. At this point it is useless that you use a HO head.

Use a HO gasket? port to match? I figured that would be the case and would only take a couple hrs to fix

If i have to use a grinding tool to match the manifold ports with the head it is not a bolt on in my dictionary.
The HO engine without its electronics and manifolds, (remember TB diameter is bigger) is just 1/2 HO.
At this point, i wouldn't bother removing the manifolds from the heads (known to be a PITA) and SWAP THE ENTIRE HEADS with the manifolds. Much easier.

I did not report anything. The only mod I had to do was the 2 bolt holes on each end of the exhaust manfold had to be open up a little. Other then that every thing bolted up.

I personally would never do that. The idea of the ports not matching would disturb me.