This car seems up my alley for a project, but it's 2 states away and there's quite a lot to research before I even THINK to get serious. Where would I start? The Shaw Race Cars website doesn't seem to immediately have a research function so my first step from the seller would be to find that out.
https://www.facebook.com/marketplace/item/269397514521459/?ref=search&referral_code=marketplace_search&referral_story_type=post
Try here, they are located in Mark Martin's hometown so it's a possibility that they are the builder. https://shawracecars.com/
That is the same Shaw however Larry Shaw no longer owns Shaw race cars but his son still works there so contacting them would probably be the way to get the information you need.
Most chassis shops keep records for each chassis they build. I have a friend who builds dirt track modifieds at HRC and they keep records on everything they do. They weld a chassis number on each one so they can look it up and tell you when it was built and who originally bought it and if it has been updated by them. I would get the chassis number and call Shaw. They would probably be more likely to talk to you if you can give them the chassis number. Will sound like your really serious and not just fishing.