probably just another 10 to 20 from the T-bar setup. Just guessing. I did got the GTS for a few reasons, weight reduction actually was towards the bottom of the reasons list. I do know that mine weighed with brakes, 130 lbs, without was around 90 lbs, stock with power steering setup is pushing 250.
This is what I got after weighing the stock stuff
stock K -frame assembly ..................................51.4 lbs
stock upper arms..............................................4.2 lbs(combined
stock torsion bars and front shocks......................22.4 lbs
stock powersteering box with hoses, linkages.........56.7 lbs
stock lower control arms.....................................10.8 lbs/pr(with ball joint attached)
strut bars..........................................................3.8/pair
stock spindles, rotors, calibers...............................98.4 lbs combined
total...................................................................247.7
since a ps to manual swap can be done with a stock k, throw out the powersteering and linkage/hose so -56.7 lbs
stocker now, 190lbs
so say aftermarket brakes save 30 lbs(using the wilwood kit i have to compare to stock)
160 is now your total weight
GTS Weight with manual rack, disc brakes and forged spindles: 130 lbs
so roughly 20 to 30 lbs. head to head, with aftermarket brakes as you have setup. As you said, most of the savings came from the powersteering swap.
Here's the thing, you can get a power rack and it doesn't weigh much more than a manual rack.......