Low oil pressure 1990 Trans Am GTA

What might be a cause of low oil pressure on a 1990 Trans AM GTA? It has had a head job and new injectors.The engine and trans were suppossedly rebuilt around 100k mi. its currently at 212k. Its not my car but i'm looking at buying it. The guy said it ran 14.8's. He wants a grand for it and i'm not sure if its worth it. He was also thinking the problem was the oil pump but couldn't it just be a regulator? ANY feedback will be appreciated.