First, How much do you want to spend???
Second, Why are you running in TTB???
Unless you have a lot more power than a regular GT, I think you're going to have your work cut out for you in TTB unless you spend A LOT. I've got a friend who runs and WINS in TTC with a 2000 GT, and he's at TTD power to weight ratio... full interior and accessories save for a rear seat delete. Again, why are you running in TTB? He has custom valved Bilsteins front and rear with front MM coilovers, 350# front springs, 250-275# rear conventional springs, Bullitt sway bars, MM rear adj. height LCA's and PHB, X2 balljoints, stock UCA's (w/fresh bushings), Cobra brakes, Torsen T2r, AND THATS IT! On 255 Hoosiers, which he usually wins every weekend NASA runs at Road Atlanta, his personal best is 1:40 and change... Very fast for a car weighing 3200# and less than 260whp in TTC.
I'm going to lay it out for you like this...
Most Important first.
Spend a little -----> Spend a lot
1- H&R Race or Super Race Springs - Not sure how well those Tokico's will handle them, but easy to find out.
2- Better shocks and struts (custom valved Bilsteins are a huge bargain)
3- Front Coilovers + Better shocks and struts
4- Panhard Bar or Watts Link(if you can afford the points in TT) (with stock UCA's back in)
4- Steeda 5 link (If you can afford the points in TT)
5- X2 balljoints
6- Torsen T2R
I'm assuming you've got WELDED full length Subframe connectors an aggressive track alignment with ~ -3* camber and 7* caster.
Your front sway bar may prove to be too much when going to the higher wheel rates... try a stock one or even smaller MM one, you'll gain more front grip and less understeer at the expense of a little lean.
I don't think you're far off from a much improved setup, but those soft springs and barely adequate dampers are holding you back the most. Then your HIGH rear roll center is going to make the car a bit tail happy at the limit, up to you if you like that or not. Lowering the rear roll center with a PHB or Watts link will help a lot with the feel , but the added rear grip will make the car understeer more unless you find a way to add more front grip as well.
Read up on Mustang suspensions here: Late Model Mustang Suspension Basics