Tim - are you saying the 55 and earlier 235 water pump can be used without adapting the block as per Dave's adapter kit? I have a 235 in my 49 and it was done by the PO. I believe it is a 1956 era 235 and the fan blade is about 3/16" from the radiator. Its scary although I have been running it that way for 22 years.
I cannot change a fan belt if I break one. I carry a pair of nylon panty hose in the glove box in case I get stranded. At least that is what I told my wife! The motor mounts are solid but I do know that one day I will have to reconfigure the situation.
I am not confident enough to drill and tap the block for Dave's adapter