I just got done putting a 55-235 pass engine in my 52-3100,I got a tell You that the water pump adaptor to use the 216 water pump on the 235 engine worked out great it puts the water pump at the right place in the center of the rad. an you can use a standard 216 water pump and upper and lower rad. hoses and the engine never has gone above 180 deg.I got mine from Jim Carter's.

Pete