The biggest thing is making sure it's unmarried. I would personally send him a message asking for a picture proving it's unmarried. You will need to contact a tuner to write you a tune for your ride if you get it. Places like Bama will let you buy into their tunes for life for like $100-$150. So for the cost of that you're almost to the price of buying a new tuner and a tune package.
Sold - Black 2000 Mustang GT, gone but definitely not forgotten
- Silver 2007 Corvette
Current - DHG 2001 Bullitt