Like I said, frame rails pop up for sale all the time on here. Whitepunkonitro, crackedback, Lee Robinson, just to name a few sellers that have them pretty often.
As far as your car, I have no idea why anyone would move the rails and narrow the track that much. Sounds like a drag race abomination to me. Narrowing the track that much definitely wouldn't help handling, and who knows what the suspension geometry looks like now. I mean, it might be ok, but there's a whole lot of things that could be wrong with it. I'm guessing, but I bet it was a dedicated strip car with a set up like that.