The small blocks are notorious for core/machining shift in the block. I had a 340 that I had to grind a considerable amount off the body of a HV pump to get it to clear the back of the pan. I also had to grind off some of a cam journal bearing that stuck out of the bore and interfered with a lifter seating against the cam lobe. When you looked at the block carefully, you could see the fore to aft shift of everything.