Something else to think about is that the GTS-T is 4.3 and the GTR is 4.1 - what affect will the ratio change make to your car?
Another option is a GTS4 diff - this uses the GTR housing drive shafts etc with a 4.3 ratio but a viscous instead of mechanical LSD.
All of the suspension arms are interchangeable between GTR and GTS-T with the exception of the ball joint that attaches to the GTR alloy upright. The other difference is the oil seal on the GTR drive shaft is different to the GTS-T one which requires the GTR housing to be machined to fit GTS-T drive shafts oil seal.
Bottom line question - what is wrong with your current GTS-T diff and rear end? If it has not broken why change it and increase your unsprung weight?
We have spent the last 6 months playing with this exact issue with our R32 that is running a RB25de from a R33. We have settled for GTS-T cradle and diff, GTR uprights with GTS-T hubs and drive shafts. Net result will be minimum unsprung weight and overall weight and with the power that we will have we should not break anything.