I say do what you want with it, I like the motivation and dedication to making something that you want. I like that you are doing it with your son.
if some of the group wants to get super critical, then I may say "you can't improve that vehicle that you have by putting a heater in it, or upgrading the seats, or better tires, or anything else if you want to keep it original. Even if you take it apart and put it back to stock you probably put it back together better than it was originally assembled. how far is too far?
To each his own. I support you, I bet it will ride nice, stop nice and go fast!
and the lucky guy that got the original running gear is probably most grateful for his gain as well.