I know everybody has pretty much chimed in and I think the last choice of just enjoying it with the son is the best . Since I do this for a living I can say the car is not worthless but with no vin ,no documentation ,no drive line ,it's only a wanna be hemi car . Without climbing all over it I would guess you would end up with close to 80k in the car fully done and it would still be a clone with a state vin # if you could even get that . If the car needs to be inspected at DPS to get a new title and they run any of the stamped #'s they could run those and find that car already licenced and that leads to some bad karma for you and the other guy .
Have A Kind Day
Mike