a bill of sale is only going to work if its from the person the state shows last owned it. Otherwise you could steal a car, have your neighbor write up a bill of sale, and now you legally own it.

Basically, there is a "grey" way to get the car legalized. Buy yourself a Hemmings Motor News from a magazine stand. In it, you will find various places that will put a lein on the car and get the title in their name. They will then transfer ownership to you. I think it costs less than $150 to get it done.