Small block oiling issue

I am having the same issue with my motor. low oil pressure to the heads. At start up I am getting 40 lbs. as soon as the engine gets warmed up the pressure drops to 20 psi and at idle drops to 10 psi. I swapped out the cam last year but did not do the cam bearings. Also installed new double roller timing chain and gears. Dropped the oil pan and found a fiber like substance in the pickup. Changed the pickup and oil pump and replaced the oil pump to distributor shaft but no help. My car has been mothballed for over a year now due to work schedule and no time to work on it. Eventually i will remove motor and either do complete rebuild or just look for another motor.