D. Scott Chatfield
I did some digging on Kadee's website and it looks like they've only done cars from Southern's 262865-262899 series (assigned to CNO&TP). These were 50-ton cars with DF loaders built in 1960. Pullman lot #8586.
This makes sense from Kadee's standpoint since they started doing these cars before they had a cushion underframe. But they could also do cars from Southern's 34903-34917 group, built in the same lot but with different internal fittings.
And now that they do have a cushioned underframe, they could do the 43000-series cars. Stick 100-ton trucks under them and Bob's your uncle.
I know I've seen a Kadee double-door 50-footer on a layout with a 43000-series number (maybe George's?) but it must have been a custom paint job, not a Kadee factory job.
Considering how many single door 50-foot PS-1s Southern had, I'm surprised Kadee has never offered one (at least to my knowledge, and there's none listed on their out-of-stock list). Since they have done CofG and Georgia & Florida, whose cars were eventually repainted Southern, why not?