... A Zinsco panelboard serving the house now?
If you can make a compliant tap, I would go that way.
The new panel needs to suitable as service equipment ... but you know that
If it was my house I would install a panel big enough for all my loads and swing them over as time permitted or just get rid of the Zinsco right then.
The Non-listed breaker is probably not an "approved" device to your AHJ.
The "reconditioned" breaker is someone else's trash with a bath. It may be fine or it may have been replaced for a problem. How do you know?
