I'm new to this forum but I feel this place can help me with my 56 Ford Club Wagon.  It has a 292 Y-Block that per the odometer has 50,000 miles.  Hopefully, its not 150,000 miles.  I've converted to a spin-on oil filter and dropped and cleaned the oil pan.  The pan must of had 1/2" of sludge and dirt on the bottom that I removed with a putty knife.
The engine runs well but I'm not getting a lot of oil up to the rocker arms. 
My question is, "What causes this and how do I fix it?"