The '55 first and older 235s are a different animal from the '55 second and newer 235. The waterpump sits higher on the older engines. It also has a shorter shaft. The water pump shaft on your engine has been shortened to make it clear the radiator. There is an adapter available to use the early engine water pump on the late engines and someone will soon chime in saying you need one. I still say if it doesn't overheat, you're OK with what you have. I ran one for years in a '55 first I had in the '80s.
