E28 M5 Gbox on a 2jz

Looking for some info.

Mate of myne is looking for a box for his 2jz going in a R31 skyline.

We have found a E28 M5 box, are these box's strong what sort of power can they handle etc?

We can get an adaptor plate made up no problem etc.. just dont wanna go to all the effort and it doesnt last.

Guy wants R4500 with clutch an gear linkage.. good deal?

thanks