you can actually find a legal bill of sale on the internet, and print it out. then just fill in the information, and send it to him to write the date and his signature.

but your problem is trying to get a hold of the guy in the first place? dang bro that sucks, keep calling and leaving messages. if you have to, you might have to just go back to his place and see him in person. hope it all works out for you.

the same thing happened to me, i bought my car in miami but i live in largo. i had a bill of sale, but i had it written on a piece of loose-leaf paper, nothing official or legal looking, and the dmv wouldnt take it. i had to send him an actual bill of sale, and he sent it back.