From what I can tell there is no source for Mopar restoration batteries at this time.
After difficulty getting through to them, I ordered a group 24 from Antique Auto Battery in early March and have yet to see it. They said they were made to order, and took around 8 weeks to fill an order. I've had no updates since, but it doesn't look like they have charged my credit card either at least!
Turbostart posted recently on E-bodies.org they are working on selling Mopar restoration batteries again, but they don't have a firm date as to when they will be available.
They said to watch their Facebook page for updates, but I am not on Facebook.
I'm probably going to gut a dead yellow cap battery I have and install a small battery inside it, as I have lost patience trying to get a battery!