What Would You Buy With Your Money?
I wouldn't even let him drive that car as it is pictured. It still has a single resevoir master cylinder and I can see the rust on the lines clearly in the picture. If that line (which is kinda out of the elements) is rusted then how badly rusted are the undercar lines. You lose one line and you lose ALL of your brakes and possible you life. A disc brake upgrade is a very good idea, but there is a reason the government mandated dual resevoir brakes and didn't technically mandate disc brake(they did mandate maximum stopping distances in 76).
I also agree that he should work alongside while the work is being performed so that he better understands and appreciates old car ownership.