I have all the parts, just need time to install everthing. This is what I bought:
Figs Full HiSteer RCA's
Figs TT Caliper Adapters
LS400 Front EBC 3GD Sport Rotors
LS400 Front EBC Red Stuff Pads
IS300 Rear EBC 3GD Sport Rotors
IS300 Rear EBC Red Stuff Pads
Techna Fit IS300 SS Brake Lines
According to Supra Forums and Club Lexus, you can MAKE TT Supra rotors fit. But I didn't want to take time to mess with that so I bought LS400 Rotors. You don't have as many choices, but if you buy TT rotors and screw them up you'll have to buy another pair.
And from everything I read here, you can us IS300 brake lines with TT Supra calipers so I saw no reason why you couldn't with LS400 calipers.
Since the TT adapters aren't made for LS400 calipers, you have to get them lined up on the hub before you can press them in. Mike suggested using a longer bolt to get things started/lined up and then press them the rest of the way in. (At least that's how I understood it lol).
I also bought cylinder rebuild kits for the LS400 calipers and my rear IS300 calipers since I had/am having them powder coated. I'm still waiting on the rear rebuild kit, that's why they aren't installed yet. If anyone wants part numbers I'll post them up when I can. And you don't have to buy the rebuild kits. I am having my calipers all powder coated so they had to be taking apart so I decided to replace everything.
EDIT: This is the cylinder rebuild kit for the 1995-2000 front LS400 calipers. These are the old boots/seals, but it shows what comes with the cylinder rebuild kit. 8 Seals for the pistons, 8 boots, 2 fittings for the brake lines, and not pictured is the grease it came with. I think that was it. I reused the two small o-rings (per caliper) that were between the two halves since you can't get them from Toyota.
Part Number is: 04479-50091
I don't have my rear rebuild kit yet, but I'll post that stuff when I get it.