'79 350 4 bolt ????????

i have a 79 350 4 bolt that chevy i have installed in my 85 k10 jimmy. i wheeled it and drove it for awhile with absolutely no problems. and then i let it sit for a couple days after i realized i had a bad universal in the front. i started it and went to move the truck and had a knock. out of nowhere!! well not really out of nowhere i guess as my oil pressure was runnin a little high then went back to normal the last time i wheeled it. i attributed it to the fact that it was 7degrees outside and it was cold when i wheeled it. so the oil was thick. the motor had sat for a couple yrs and it had oil changed b4 it was pulled from the donor truck. i put bout 250 miles on it and changed the oil again the day b4 i wheeled only i didnt change the filter that time as i didnt have a big enough filter tool. i had changed it b4 at my neighbors where i got the motor. well after 250+ miles it has gone to dirty a** oil already. i personally think its the pump or the oil pick-up bad or it sucked up some funk from the bottom of the pan. is there any way to check this w/o blowin the money for a new pump or an aftermarket pressure gauge? should i just drop the pan clean and check the pickup add fresh oil and see what happens? if it matters the knock/tick is comin from the drivers side front of the block