How far back into the tank does the 1/2" pickup go - enough to insure it doesn't get uncovered on acceleration? Where is the fuel filter in relation to the pump, and how close is the pump mounted to the tank?

Personally, I do not trust any in-car mounted fuel pressure gauge. The positioning of those isolators can be tricky, and have heard guys say they get flaky readings from them (assuming you are using an isolator, since the gauge is inside the drivers compartment.)