Dunno what your budget is and I confess to not having read the entire thread but....
You may want to give the folks at Pac-Nor a call. They're a small company that does custom barrels for the extreme-accuracy crowd. I deal with them at work and I will say that I've never been disappointed by them. Their quality is excellent, and here's the part that's important to you: You send them a drawing for a barrel and they'll make THAT EXACT BARREL happen.