340/420 90psi Oil Pressure During Prime

I just finished priming the heads. When I took the valve covers off, oil was already dripping down the head. So I used another slower electric drill (0-800rpm) and while watching all 16 rockers until they pushed out oil, this drill showed 90psi too.
So the valve covers are back on, its primed, and cleaned up and ready for the intake.
Thanks guys!