1996 Chevy Cheyenne sudden drop in oil pressure

1996 Chevy Cheyenne mileage: 128,000. I have a question concerning the knock in my engine. I was driving down the road this weekend when I had a sudden drop in oil pressure and my engine had this awful knock. I took it to Napa and pulled the lifter and push rod and the one I suspected was not bent. I think it might be a flat cam or I threw a bearing what do you think? It still starts up but it sounds awful. I am going to buy a master rebuild kit today and I am going start as soon as possible. I am just pulling the engine; any pointers on what I will need to rebuild the engine, I have a Chilton’s manual and a lot of tools just want to get a head start on what I need before I have to run back and forth to the parts store.