If the PCS/EPC is the issue then the shift kit would bandaid/help with that and keep you from setting the P1811 code. When the PCS begins to give trouble, it'll often set only the P1811 and cause harsh shifts.

If you are rebuilding, I'd also suggest sending your valvebody/channel plate to Dave and have it gone through. When you get it back, it's bolt on and that saves a lot of questions/time/aggrevation.