It's not numbers matching. The body is a part, and the other parts don't belong to the body.

Technically, it cannot be numbers matching as many of the factory stamped VIN numbers will not be correct. Close inspection will always reveal the welds that have been done, and the modifications done to the donor car. It won't be an investment quality car.

If he's up to the challenge of building a basket case and plans to keep the car and not sell it as numbers matching, does it matter?

Which title does the car have? Donor or crash victim?