You set the boost control valve to 0 duty cycle and it still overshoots the wastegate spring pressure by that much?? I have the 10 psi spring and it barely creeps above that on a hard pull if set as I mentioned.
As for the clutch, I was going to say that you could probably just use the sprung disc that comes in the 850 SO133F kit since it's probably the same thickness, but the input shaft on your trans is probably larger? I think it changed in 2002? That's not to say that they wouldn't have something suitable. Maybe try contacting Spec, but I would wait until you have the clutch out so you can determine what exactly went wrong.