I lucked out with my '53 in that I had a 54 full pressure motor which was the last year for the old style water pump made it an easy swap. As mentioned you can adapt that early pump to any 55 and later 235 no problem. BTW I used my 53 bell housing, flywheel etc etc.
Best of luck
Jim


It's easier to get forgiveness than permission!
1946 1/2-Ton Chevy
1953 Chevy 3/4-ton Factory Stakebed