It's looking great and very professional. Congratulations.
Regarding the voltage regulator, since the Patrol doesn't have an indicator light in the panel, a number of voltage regulators can be installed (adapted). I've tried to glance from the pictures that you've posted, what type of connector that electronic voltage regulator has. My guess is that it was probably adapted at some time, but it could be also an aftermarket for Nissan (almost all Nissan vehicles with an outside regulator used the same one with different part numbers).
If that regulator is still with the original harness connector (rectangular with 6 spade type terminals) then this could be a good choice: ACDELCO E660C (available at Rockauto among others)
If adapting another voltage regulator, this is the one I've installed on mine: MOTORCRAFT Part # GR540B (also at Rockauto) Will need also the connector. I can send what terminal goes where. It's possible that you have now a similar one installed.
Please note that in an alternator, the voltage regulator controls the field voltage of the rotor, and not the total current output that is the case of a generator, so any voltage regulator can be adapted. Generators on the other hand are very particular and require a dedicated one.