There are LOTS of sources of information. IF the building is of local, historical significance (which you say it is), then the area libraries may have pictures and books and such. Also, your Local Preservation Society, Historical Society, AND residents can help.
If you can work with your local newspaper(s), perhaps someone can write an article about your plans and ask the public for pictures and 'testimonials' about the building. Together, you should get a pretty good picture of the place. Also, if there are other buildings built by the same person/people/company, contact them. And if not, perhaps there are other people/companies that built at the SAME time (in history) and can give you insight into the building and its builder(s). In other words, there might be a famous woodworker that worked in a number of buildings at the time. He/They may be able to help you if there is surviving family.
In short, you need to research the building. Start by searching the WEB. My best to ya and hope this helps.