erm..... I think it is probably not much different from a fully laden 3sgte to be honest. I have a 250kg electric crane in my man-cave which can just about lift a 3sgte and box (or 3vz with box).. However, when i lifted this out of the trailer it didn't even break a sweat, no sign of strain.
wiki page >>> http://en.wikipedia.org/wiki/Toyota_UZ_engine (no weights on it unfortunately)
So I reckon I am probably 15-20kg's heavier than stock though balance should be better...
Remember though, this is purely a (very expensive) engineering exercise. If it drives well it'll just be an added bonus.