I think the best approach for a Fallout Pen and Paper would be All Flesh Must Be Eaten + All Tomorow Zombies, which is basically a D20/Gurps hybrid.

I once played a tabletop version of the SPECIAL rules, and I found it terrible. The game moves with the elegance of a beached whale and especially combat are a chore. I would recommend something different as a basic system, as these rules just don't work well on the game table.