We just stripped several layers of paint and 98% of the Zolotone on the interior of our '56.
It's gutted and we are replacing the floor - so it's gone too. We used two different 'safe' strippers because it is enclosed and overhead. We used Napier Remov-all and Citristrip. Both worked. Citristrip smelled 10X better than the Napier and it's readily available at Home Depot whereas we had to order the Napier. We applied one coat, let it sit for 10-15 minutes then power washed it off. I think the Citristrip worked better than the Napier in one coat. It was not our goal to go down to bare metal because we are going to re-Zolotone and wanted to leave some "tooth" for it to stick to. I'm certain the Citristrip would take off all the Zolotone with another coat, especailly if you don't have all the latex paint we did over it. Napier might do it in a second coat, but most likely two.
You can see our results here