It 's the little things that you want even think of that will trip you up. Their are a number of differences on a conversion of this nature
Vehicles New Zealand new or Japanese imports
Wiring for auto to manaul and you mention Zf different again,
vent piping eml different diameters,
A/c left side for the N42,46 right side for the M54 pipe work change over, wiring lengthen and re-route,care of the connector on the a/c pump they brake real easy.
Ignition key an barrel all door locks etc check to see if remote access is inferred or radio on both vehicles
Heater control valves, system auto or manual type
Exhaust, pipe diameter mounting points. mufflers
These are a few things that come to mind. It makes for a great project hope you keep a record and let us all share.Plenty of info and people Ray and Brent who have practical experience an can help out best of luck