You should put your gtr centre into your old diff housing, and use the crown wheel off your old diff.
That way your ratio will be the same, and you will still have your abs sensor where it needs to be, and you'll have the good lsd.
Then, use the gtr axles and hubs. The axles are bigger and the hubs are alloy which means they are less unsprung weight. You will need to use all the gtr arms.
Your diff will fit into the gtr cradle as long as you use the rear cover plate off the original diff, and also use the original front diff mounts too, as the gtr had big rubber mounts on there's.
PM me if you need any more info., I've done a lot of work with diff's and rear end setups.
Thanks, Scotty