I know you want to avoid the idea of removing your radiators, but chances are, they are plumbed with the original steam pipes, wrapped in the original asbestos insulation, full of water that has been in the system for 30 years. ugh!!!!
Check with a boiler serviceman in your area, there may even be a sticker from the one who looked at your system last time, and have them give you an opinion, but I would recommend pulling the radiators, having them sandblasted and refinished professionally, and while you're at it, look at replacing the boiler in the basement with a more energy efficient model, replumbing your radiators at the same time.
This would cost quite a lot, given you would have to have the asbestos abated by a professionally licensed company, but if you truly want to restore, this is something to think about. At the very least, make your decision based on facts. Get 2 or 3 bids from reputable local companies on the cost of removing and reinstalling the radiators, then decide whether thats the way to go.
You may even decide to deep six the radiators altogether, installing a central forced air gas furnace, and reinstall your "new" radiators strictly for looks...