Glen,
I hold Landrovers in some esteem as I learned to drive in one back in the fifties!! (Yes, I'm that bloody old......

)
The Isuzu motor enjoys an almost supernatural reputation. Full confidence there!!
The Lexus V8 uses the A340LE four speed/lockup Toyota transmission, the 7MGE six uses the A340E, which is almost identical and the same physical size inside and out. It fits fine!!
Ah, StarBucks! How could I forget? Even good coffee beans brewed for some hours tastes a little, um, different.....
The electrotrickery is not easy, granted, but the V8 comes with ECU, full loom, integrated TCU, and the only external wires are starter, alternator, cruise control, ABS and fan control. It won't be easy, but with measured care it is quite possible to negotiate with some help from the forums.
Cheers,
Hugh