overheating

[53burb]

My engine is getting hot. I know the sender is correct because the engine overheats and the water boils. The problem started a few weeks ago. I thought it was the thermostat. I have replaced that. I have replaced the engine. I have replaced the radiator with a 4-core unit (not new). I replaced the fan clutch. The fan only sticks out of the shroud about 1/2 to 1 inch. The upper hose gets pressurized. The only thing I can think of is the water pump. It was replaced about a month ago. I started having the problem after that. I replaced it because the original one was leaking from the weap hole. I checked the p/n they gave me, it was the right one. Do they happen to make a reverse rotation short-style water pump?? I know somebody mentioned this before. The only thing I can think of it got put into the box I needed by accident. Anybody got any other ideas???