By top piece, are you referring to the whole windshield frame as in the title or just part of the frame? I see this stuff on flea-pay now and then but not often. There might be stuff on the swap meet section.
Being in the sunny Phoenix area, Sammy Guthrie of Arizona Model A probably has lots of open car parts. Great guy, and very knowledgeable and friendly. 480-782-0266.
Marshall