Set it to 39 psi with the car off. You can force the fuel pump to run (not sure if it works on 95) by jumpering the fuel pump test lead to ground with the key on the on position.
There actually is no precise fuel pressure to set it to since your computer will adapt the fuel delivered based on feedback by oxygen sensors. Just make sure that you don't set it too low or your spray pattern will suffer and your maximum amount of fuel delivered will be lowered. Fuel pressure only relates to fuel throughput, not air/fuel ratio.
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351W 89 Mustang GT Convertible