I reckon it can be done. I have often wondered about doing it on my 58 Imperial. I pressed the rear brake drum/rotor off the hub and did a disc brake conversion on my Imperial but still used the same axle/hub. Never went so far as using a 1 piece axle. Interested in the responses to this thread.
I haven't tried it but have been told by someone that I consider very knowledgeable that it cannot be done because the housing end flanges are different.
I converted a 64 B body rear. Used OEM B Body one piece axles with green bearings and matching 10x2.5 brake backing plates. You need to install longer axle end studs.