The most ideal engine for the 3 door Nissan Patrol is a 1FZ-FE. Not only has the conversion been a success on Shabab's Untame Safari, I was very surprised to see that almost all the 3 door Patrols in the UAE run on the 1FZ-FE (they fit x-large and twin turbos on it for desert dune climbing). Understandable thats a very expensive engine (~250k+) and probably not what you would go for.
On the 1UZ V8 and 5VZ V6, I think its an interesting comparison which we have briefly debated here before. Both are damn good engines and are about the same price these days (~100k). The 1UZ being somewhat rare but by no means uncommon while 5VZs seem to be flooding the market.
If you have a good mechanic and an even better electrician, I feel that both can be made to work well with the Nissan Transmission and diffs. The 5VZ would be fundamentally much better suited to a heavy-ish offroader, the 1UZ would be quite uncatcheable on the road, literally. The 5VZ would perhaps be more reliable/rugged given simpler wiring, the 1UZ would be quite indestructable if wired and mated properly (clutch plates notwithstanding). The wiring on both the engines is not really simple but the 1UZ has some added complications and complexities.
In a nutshell, I feel the 5VZ is the sane/decent choice while the 1UZ is the wild/wicked choice by all means.