Give me the VIN and I will run a carfax for you.
The exempt of the mileage law will be determined in the state the car was sold not delivered. Find out what that state law is. Iowa; 10 years ( miles exempt along with damage disclosure.)
The crime here may be jumping titles. That is illegal in my state and most states. He did not register the car in his name before selling it to get around paying a state tax of some sort. Do not lose that proof which means do not go title that car yet. Call the attorney general of the state where the car was sold and report him if it's illegal. They in turn will investigate if in fact it's against the law to jump titles. They have people for that trust me and they love their jobs. In Iowa this is a serious crime. People do it all the time to avoid taxes but you don't want to get caught.
Now with all that said here's what I would do first. Do your research like I said above. He is probably exempt from odometer fraud (because I would bet it won't fall under fraud do to age) but not jumping titles. If you want to keep the car but felt you paid too much then see if you can work out a deal with him before reporting him. He doesn't want the DMV at his door if it's illegal to jump titles and he did it. If you don't want the car then pursue that option with him.
If you can't get ahold of him the DMV will know how and guy's like this know it. I promise you he is reading this thread so here is his warning.
Good luck and send me the VIN