I emailed Mr York last night with my various ideas and the reasoning behind them. He said it wouldn't be a problem. A 376 groove diameter, 1 in 18 twist cut rifling and a chamber/leade favorable for cast would run me $275 plus shipping both ways. He said turnaround right now is 4-5 months due to him moving his shop location and being in limited operation or downright closed till the move is done. This last bit is bad for the "immediate satisfaction" problem I have.
I think I'll have the 223 barrel mounted on my BC frame and request a BC forearm. I'll also order the extractor claw for the 38-55 as well. I'll figure out sights later, I'll probably end up scoping it with something low power, in the 2-6x range.
Ian