You might want to look at Plastructs styrene sheets. Look at their catalogue, pages 53-57
https://cdn.shopify.com/s/file...0_CatalogSMFL.pdf?53
Also look at the N Scale Architect:
https://thenarch.com/catalog/b...-scale-sheets?page=1
Architectural model supply houses may also be able to help
https://www.modernss.com/colle...riant=23686175948858
Looks like a fun project!