These cars never hit the yard here, have to watch for partouts, and if you're lucky know people that deal in a lot of parts cars.
I have a friend that has a fair amount of G body stuff, nothing spectacular or rare, but has some good stuff from time to time. Never pays much for what he buys, describes himself as a "bottom feeder" at auctions. Is now to the point that people bring him their lost causes, and he parts what is worth selling.
I'd be tempted to repair the major damage to the existing dash and use the cover for it. I bought a nice used dash once, only to have it turn into a cracked mess inside a year. Just hate to see money spent on a part that is probably only going to get worse relatively soon.