There should be plenty of 12 volt Delco parts, and good-quality rebuilt units around. Getting an armature rewound and changing field coils might be necessary on really rare stuff, but with the untold millions of Delco units that were built, it's hard to imagine they would be that scarce even now.
If you can't find something suitable close to you, drop me a PM. I have connections with a couple of oldtime rebuilders who can make your parts look and perform like new, or swap with you for a good-quality rebuilt.
Jerry
