Is the radiator clean and in good condition? Normally, there's not that much of a problem with overheating when going from the 216 to the 235. Another option would be to use the adapter for the 216 water pump which also positions the fan correctly and allows for a bigger-diameter fan blade.
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!