If I understand you correctly, you have a short shaft water pump on your 235, therefore, your fan will ride lower on the radiator. My COE has the same setup and overheats at parade (walking) speed and does just fine at all other times. I don't think you get efficient cooling at very low speeds.
I would be concerned that a shroud won't fit with the low set fan. Pre '68 Dave above may have the solution with his adapter plate that centers a 216 water pump to the radiator when attached to a later 235.
Kent
