Just buy another dash off ebay and use that if you want to save your original. Or better yet, buy a cleaner one and use your original. But I'm curious why you would want a cherry dash sittin in the rafters while you're driving your car? Put the good stuff in the car and enjoy it, when it goes bad, restore it. I personally wouldn't go with a cap, they're cheap and look like crap. Plus 100 bucks for a thin plastic shell is too much, you could buy a good used dash without cracks for that much.
good luck
good luck