The safest level is always about 40-42 psi. Once your chip is in, and the BLM's have stabalized. tweak the fuel pressure only if the idle cells are outside of the 115-140 range.
As long as the BLM's are in that range, you're running stoiceometric, and should have no problems. Once you try fooling around with extremely low fuel pressures , things will run leaner than it should and this is what drives the HC's way up.