Matt ,
To try and make it look period correct with todays paints may be stretch , as they were painted with Nitrocellulose Lacquer and hand rubbed via an oil rag from the factory ( my grandfather did this as his job at mercury )

I do know you can spray lacquer clear over PPG's DBU base after letting dry 1 hour , as thats how PPG recommended doing it when it was first introduced , or spraying their Deltron DAU 82 uerathane clear over it which is not made anymore .
Using a single stage may work but may have to much peal for a factory look unrubbed .

Maybe if you used the lacquer clear over the DBU , and gave it a hand rubbing instead of machine buff , may give it a correct look .

Spray