Windmill Class Association

I am in the process of restoring a wood windmill. The boat was given to me as is and as a result is missing some hardware. I am to the point of needing to connect the main shroud to the deck. What is the best method here? My reading tells me that chainplates should be used. However, I don't see a structural point to attach them. I must be missing something obvious. Any advice is appreciated and thank you in advance.

-James