Okay, I will say this. I have seen applications (and tried them) that "decode" a FAS file, but i will never give anyone the location to where i got it. Besides, its a waste of time. For the most part they are garbage. If you have the source, use it. If you don't have the source anymore, re-write it! (It would be good practice. And you will prolly end up with a better progy anyways.)
I seriously doubt that anyone who has tried these tools will give them up.
Will, seriously, It sounds like this would be a good time to start over. Define your scope and start assembling the pieces.