Lew,
Let me know what you find out. I'd like to maybe do that as well.
I think the problem is going to be the diameter of the barrel. That original is an inch at the breech or less. Would make a beautiful slim gun. But I doubt most of today's barrel makers would ever make one that thin.
The closest I know of right now, is the custom 46" B weight .50 that Rice started for EK. They are one inch at the breach and can be either smooth or rifled.
If Rayl doesn't work out, I'm planning on going with this one.
Again, let me know what you find out.