Evac54, I attached a couple snips from Patrick's website that might help.
www.patricksantiquecars.com. You might want to give Patrick a call. He is a wiz on these old engines, particularly conversions. He is a great guy to talk to.
It seems to me that you need a fan spacer to move the fan out a bit from the harmonic balancer. Patrick refers to a spacer in the text of one of the attached snips. Consider starting from the radiator side of the fan instead of the harmonic balancer side. The tips of your fan blade should be about 1/4" from radiator. If you can use a spacer to push the fan out to that point, would it give you enough clearance for the harmonic balancer? If so, simply find the correct size spacer. Perhaps Patrick has one. (Word of caution...if he doesn't have one in stock ready to ship, you might want to explore other vendors because it could be a long wait to get the part.) Do a search for fan spacers on eBay or vendors such as Summit Racing and you will find options.
Note in the attached snip referring to the spacer, Patrick also mentions that the fan might need to be 'untweaked' to clear the harmonic balancer. You might want to ask him what he means by that and what is the best way to 'untweak' before starting any surgery on the fan. The snip also shows a picture of a fan that is supposed to fit, but it might be what you have.
You asked if you purchased the correct water pump. Probably. You asked if you can use the later model fan that came with the 235. Based on the Patrick's info, the answer is yes with a spacer.
I hope this helps and doesn't confuse things further,
Matt
PS--Here is a little info that might help with the harmonic balancer/pulley size questions. The '53-'54 235's with the high water pump in the same location as the 216 came with a harmonic balancer with a 6" pulley for a 3/8" belt. The '55-'62 235's came with a 6 3/4" pulley and a 3/8" belt for cars and a 1/2" belt for trucks. The smaller pulley of the '53-'54 harmonic balancer will turn the water pump and the fan slower than a larger pulley. One of those would be ideal to use on one of these conversions, but they are hard to come by. As Pre68 Dave points out in his article, if you can't find one of those early 235 harmonic balancers, use a later one made for a 1/2" belt but actually install a 3/8" belt. Why? The 3/8" belt will sit deeper into the groove acting to reduce the working size of the pulley and as such will turn the water pump and the fan slower than a 3/8" pulley with a 3/8" belt. Even though both pulleys have a 6 3/4" diameter, the working diameter of the 3/8" belt recessed into the 1/2" pulley is less than a 3/8" belt in a 3/8" pulley. Would a later harmonic balancer that came off a car with a 3/8" pulley and belt fit? Sure, but it will spin the water pump and the fan faster.
