The last six numbers are the build sequence numbers, and as stated before , the plant code is Hamtramck and the engine code b, is for a 6 cyl engine.
I dont see any way to properly decode this car without the original dash and fender tag. If he doesnt have those, the car will have to have a new vin assigned and will never be a numbers matching car.
My gut feeling is that he got ripped off by some charlatan trying to make a quick dishonest buck.