Good luck, dawgfan! I've been looking for a metal top cover for a 2250B for months now. I've ran ads everywhere I know of and have had absolutely no luck.
In both your cases the most likely path is finding a parts unit. You just don't see that many people 'parting out' vintage receivers and not likely that any repair store has old stock on cosmetic things such as covers and face plates. Besides a parts unit might provide other spare parts you might need in the future.