Yesterday, I decided to bite the bullet and take a chance on powder coating the deck. I found a local coater that was able to answer my questions and found out that I run the risk of a "pebblely" surface due to out-gassing of the magnesium. It would also cost me stupid money to get an exact color match, so I opted to go with a color that is a bit darker with a sort of rougher texture. These things don't bother me too much because I like to use the mowers I collect. In a way, I hate to get away from the original look, but maybe this will not look too bad. If the final results don't look too bad, I may go this way in the future. We'll see.
It will be a while before it's done but I promise to post some photos with the results.