If the pump impeller protrudes into the block, you have a newer engine than the truck. The only 235's with that type of pump are 1955-up, and the pump has to be modified by pushing the hub back on the shaft with a hydraulic press and cutting off the front of the shaft. Somebody at one of the resto-ripoff places sells an already-modified pump, but you won't find one locally.

This would be a good time to swap to the high-mounted 216-style pump by using the relocation plate Pre-68 Dave sells on Ebay, which will also position your fan in the proper relationship with the radiator.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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