1967 Dart Power Steering Pump

Hello, I have a 1967 Dodge Dart Convertible with a 273/2 barrel with a leaky power steering pump. The car is a daily driver so I'd like to minimize the down time. What I do now is keep spares of a lot of parts myself so I can change things out without having to wait around. Problem is: I can't seem to find a new pump for the car.

So, I'm looking for the best option to get another power steering pump to go into this car. Could be either:

1. A new/rebuilt one that fits the same mounting hardware.
2. A rebuildable core that fits the same mounting hardware.
3. A new/rebuilt one with a different set of mounting hardware.

Etc. So ideally the same one but if that's too hard to come by retrofitting a later model one is OK too. In the end I want to have two that I alternate installing and rebuilding. Here are some pictures of what I have now.

Thanks for any help

Maurice