Unless state law in MA is different from here, a car has to be a certain number of years old before it can be legally transfered without a title. I'd check and see what the law is there, because unless the car comes under such an age law the guy you're dealing with is NOT the legal owner, the guy he got it from still is as far as the state is concerned.
https://secure.rmv.state.ma.us/TitleLookup/intro.aspx
Here's another link about this...
http://www.mass.gov/rmv/titles/index.htm
Caveat Emptor dude. Don't hand this guy a damn thing until you know for sure what's going on.