Actually, to get a bit more specific...she signed the bike over to him about 2 1/2 years ago and he did the typical dumbass thing and never got it put in his name. He rode it with someone else's tags on it and no insurance. I knocked off a part of a debt he owed to me when I accepted the bike and I did a carfax report as well as had a police run the VIN on it. Everything came back clean. The title and bill of sale he was given are lost at the moment. This guy is not the most organized individual I have ever met. However, they do exist and are signed by the ex girlfriend wherever they are. Therefor, if she does report it stolen, and he finds those papers at a later date, she will be in a legal issue of her own. The only reason she won't give me a title is because she told him that she wasn't going to help him out at all due to some hard feelings between them. She won't go get a duplicate title...I even offered to pay her some money for her trouble.
So, back to the original question and point of the post, I am looking for alternatives (thank you criomega for the suggestion, this is more what I had in mind than a lecture about buying things without a title). However, I am wondering if it might be easier to switch out the frame as I have pretty much purchased all new parts for this bike at this point anyway...