Are you to say you have a 203 that needs replaced or rebuilt, or you just want a 203 new or rebuilt and you don't have on.e
If you have one, I would just recommend you find a shop near you that you trust. POst in the regions forums here to mabey find one. I know a really god one in Saginaw, MI, but I didn't look at your profile yet.
If you don't have one, you need to get one. 203's are pretty cheap. If you go someplace and say I want a new/rebuilt 203, they will rape you for a "core" charge. Go spend $50-$100 at a junkyard, then rebuild it.