Those shims adjust caster and camber. It sounds like your front end has a less than professional alignment. It probably doesn't matter at this point, since you will have to have the front end aligned when everything is put together.

It would have been a good idea to count the shims on each bolt and replace them as they were. I'm gussing that didn't happen. How was my guess? Even with a bad alignment, it probably would be closer than pulling them out.

Long story about how his dad won't know . . .
Dads usually know more than you think they know. If you go through with this, and he finds out, you may be out both your money and the engine. I'm assuming that the son is under 21 doesn't have legal authority to sell - particularly something that isn't his. Some fatherly advice: in your hurry to get a motor, you may be assisting in a crime. Think about it.