Boogieman! On your '40, the question isn't one of theft, as there (I assume) is no re-stamping of the first digits of the VIN. That's why in Illinois, your bill of sale, and a title bond, and maybe an affidavit from a dealer or two, might pass allowing for legitimate re-stamping.
They then get picky about whether or not you have the entire bike, etc.
Every authority is different.