Is it at all possible to just "port" it in, directly? Or would there be more involved than that... I suspect so. Otherwise, I suppose, someone would've done it already.
But anyway, I'm curious, and it would be glorious to see FO3 as good as it could be. Really, if you haven't checked out what OBGE can do for this kind of engine, I recommend doing so - it's stunning. And only getting more so, month by month, or so.