Nice, especially since Fallout's perk system was pretty much 3E's feats (not that one borrowed from the other, they're just very similar) it should be very easy to translate them.
Why not just use the SPECIAL system? It's pretty easy, you just need the numbers on range, light level, and equipment.
Because the SPECIAL system, is a bastardized version of GURPS, if you're going to use a bastard system, may as well use the system proper.
I am not a big fan of roll under systems, as most of them are poo, and I don't like the feel they give in general. GURPS however, along with BESM 2e, are the only two systems that do it well.
The SPECIAL system, is a bit to light for my needs, requiring more work to get the characters I want, and more cheating to get the creatures I need. (This is in due to its lightness and my unfamiliarity with it.)
Its also a new system for me, and from my experience for forum games, it best to run systems you know pretty well, to help adjust for the inadequacies of the medium and limit their impact on game play.
Without relieving a lot about the plot the Enclave, or Super Mutants won't be the main antagonists. To keep in spirit with the game, I won't be dictating the moral compass of the player group, because of this and the nature of the universe it'll have the 'Mature Flag', and a needed declaration of 18 hood to play.
It won't be taking place in either two parts of the country in the three previous games nor New Vegas. After just rereading The Postman, probably Utah area with probably some peeps and locals from it, with the fallout twist.
I also run one or two minigames, such as spot the pun, or spot the reference with the reward generally being an additional Action Point.