The only 235 that works with a 1951 pump (which is for a 216) would be a 1954 or early 55. 55 2nd. and later engines use a low-mounted pump that sticks back into a hole in the block and puts the fan too low to cool well. There is an adapter plate to mount an early pump on a late block, but it requires drilling and tapping two holes in the late model block.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!