If it were me and I was financially stable and came across that kind of "free" money. I would donate a bunch to all the great guys here on the board to help with thier cars, keep everyone on a level playing field.
Seriously like Mark Y said more info is needed. But is the money gone already for the 00 Boxster? I would make the 74 into a track car and keep the boxster for the road, or even keep those two and build a track car.
Shawn