I ask this from a position of not knowing what the differences are between the two motors with regards to electronics ans systems like variable cam timing that might need to be controlled by the electronics.

So why not drop in a 5vzfe where a 3vze once lived and run the 5vze with the 3vze wiring and electronics. I know there are logistical problems, like the fact that many major components, like the air flow meter, may be on opposite sides of the vehicle. -- Matts

'89 4runner SR5, 3.0, auto (fun)
'93 xtra cab, dlx,3.0, 5spd (work truck)