My 01 dodge truck, 318 has been having oil problems. the oil pressure quit showing pressure at all! i thought it might be the guage but if you drive it the rockers start getting a little mad! engine temp never rises, but no oil to the top end.

ive searched the net and lots have this issue but no one has an answer for it.I bit the bullet and changed the pump to a h/o pump with no change.
My question is.

#1 is my engine shot?
#2 could the pump drive have broken?
#3 could i have a blockage in the motor preventing oil from circulating?

Pan and pump screen were clean when i pulled em! no sludge buildup on the bottom end, and no debrise of any kind.

Thanks