Should I be pissed that it's not an 8 3/4?

As usual, its "Buyer Beware".

Whether he told the truth or not is irrelevant at this point. Its up to you to do your homework before you buy anything. You didnt know what you were buying, its possible he didnt know what he was selling.

I have bought things that were not as they were represented. Ultimately, it was my fault for taking someones word for it, and being too trusting.

At this point, you dont have any legal grounds to stand on, and your chance of getting anything back are pretty slim. Chalk it up to experience, and move on.