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The first thought is that Fusick might have something, but they don't. They have battery trays, but only for 1965 and later. I don't know how the '64 battery tray differs from the later ones.
You might have to go with a generic aftermarket. Measure the space for the tray and see what's available. It's not like anyone actually sees the battery tray, so the fact that it's not stock will probably go unnoticed by anyone looking at the engine compartment.