I face the same problem, putting together sources for materials and parts that can be assembled into a top for a Kirkham slabside. Here is a source for good quality top material:
The Haartz Corporation - Cloth Convertible Topping
I'll ask these folks to build side-curtain frames from the specifications I provide:
https://www.europaspares.com/product...S___CSSS_.html
A lot depends on the ability of local craftsmen to fabricate a custom top and side curtains when the car is available to them. There are a couple of shops in Montana whose work crafting interiors and tops for hot rods is first-rate. I don't know yet how interested they will be in building weather gear for the slabside, or what they will charge for the project. I prefer making the car available to a local fabricator to sending measurements to a shop out of town. That way we can discuss the advantages of lexan vs plexiglass, top and liner materials, all that sort of stuff. And the builder will have the exact angle of the windshield to the body and the locations of the ferules in the doors. These I believe are critical to building a top and side curtains that work on a replica at least as well as the originals.