It's a great idea provided you don't let jr actually use the car until about age 27ish. Talk to Dave at GPR. He has 1/2 of a very nicely restored 914 that a dad gave to his 16 year old. After one week, the front half was wrapped around a telephone pole
Even the most well ballanced kids become slightly psychopathic in the company of their friends. Get him the 240. We had one (okay a 140, but same idea) many years ago -- not exactly a babe magnet, but it was a solid, heavy tank. Good transport and very safe. Get the 914 for you and your son to work on together and drive together, but save it for him until he has the maturity to appreciate it and care for it fully. My 2 cents.