I second the marine upholsterer.
The MG Magic parts are perfect for old CMCs and Fiberfabs, but the BCW is a little different. The front windshield bow is a different design (a block of hardwood), the connection is different—pins from the windshield frame and thumbscrews in the top—and I suspect the dimensions are a little different.
Any good boat place can make the two-bow frame. It’s much like a bimini top.
I can send you pics and detailed description of the rest.