The blue-handled tandem breaker is an early version of Westinghouse's (later Bryant) twin. That's definitely a Murray panel. I also think it's safe to assume that the switch on the ceiling is a disconnect for the furnace since the red plate screws are still in it. I guess they wanted to be careful and not lose them!
What exactly is the origin of the "interchangeable" bus stab? I've heard Westinghouse, I've heard Sylvania. I have a Frank Adam panel from the mid-50s that looks like it would probably accept a BR or a QP. And then of course in some panels, a competing breaker will "fit", but only if you really hammer it... not that it will be Code-compliant if you do.
