Availability of parts is most important in my view. VVti electronics are slightly more elaborate and still not so well understood generally. Also, the 1UZ vvti adds not all that much in terms of power and torque unless you need the extra 30 BHP for a specific purpose like racing or something. Lastly, the older 1UZ sounds a quite a bit more brutish in stock form and kinda suits the 60 series more. Nevertheless, the vvti version is also pretty much the same thing otherwise and if you want to go for that, its always very possible.
Clutch work may need flywheel, clutch plate and pressure plates from different Toyota models depending on the gearbox. Some redrilling of holes is also needed, but I am not fully on top of what goes where, all I know is that if its done right, the desi jugars holds up well against 260 ft lbs.