With this post, I expose to you my deepest vulnerability; the most virulent of all my bêtes noires.
I accept that—with a little interpretation, perhaps across a noisy room—the words “have” and “of” could be construed as homophonic. However, to follow the past tense of “will,” there is only one possibility from the two choices presented.
Would HAVE. At a stretch, I’ll plump for “would’ve.” But please, never “would of.”
What better way to advertise that you were thrown out of a stonemasonry apprenticeship for being less erudite than the very stone you were working, than to say “would of?”