Glad you found your problem. The tc3 is famous for requiring lots of work just to go straight. Springs : gold /blue and silver rears are all you'll need. Maybe green rears and silvers fronts but that's really soft.
Green slime helps a lots to build smooth shocks.
Measure everything with digital calipers, ( also measure the lengh of the springs) and it should work OK. I've had two springs from the same color rate have a 1 mm difference at times, that's HUGE but the material they are made of is very good nonetheless, so just compensate with the preload collar.
I love wedge bodies. I love dish wheels.