Did you do any cleaning when you checked for debris and sludge? Run a wire down the supply holes? All of them?
The pinch in the line over the rocker shaft is to force the oil to the ends of the rocker arms; sludge build up could cause the #1 rocker arms to just dribble, or the rocker could be worn down enough to block off the oil supply.
That is a good oil pressure reading, but I'd be wary of trusting it alone if it's the original mechanical one- what year engine is this?
Brad
