well i think your creating your self issues. If you have a PPE box for a LB7 yet your running a LBZ FPR, i dont see how it will work. specially since we had that whole big thread where Dan stated the control boxes wont work from LB7 to LBZ and so on. Now i could be wrong as ive yet to try this but im jsut going off what was said.
if you swapped the LBZ reg to the valley pump, put the LB7 reg on the second pump on the side and tuned the LBZ reg to work for your truck i can see it all working like it should.