What would trigger the need/desire to upgrade from the 10dn, for you? On my newly acquired 69 Electra parts car, I have installed a 94amp 12si, but that was driven by a 10dn with a cracked case, and already having the 12si sitting around in my father's shed.... Although it's a rebuilt unit, it actually came off an Olds that I grew up with. I'm wondering what/if I should do something similar with the LeSabre that has a good working original (to my knowledge) 10dn to something else. The Lesabre has electrical issues, that are alternator independent and will need their own solutions.... dim headlights, and tail fuse blowing. Do the external regulators have issues?
Everything has issues on a 50+ year old car. But, if its working leave it alone! I would not replace a working alternator/regulator unless and until it breaks or I have a need for more power (amps). Like if you install an electric fan or a huge stereo for example. Track down each problem and solve it.