Re: I need advice on compatibility between the engine and gearbox
Swapping a 4.7L High output in place of a 4.7L is possible, but needs some extra work. You will need the PCM for the HO engine and the engine wiring is different, since the HO engine has knock sensors. There is a writeup on this type of swap, just use the search function
Regarding the T-case, originally both 4.7L and 4.7HO come with the NV 247 T-case.
Now you want a NV 242 T-case. Mounting lugs are the same, you probably will need a different rear propeller shaft and the selector lever. This swap is also done by others before, not sure if there is any writeup on this.