I have pushbuttons as well, but they have to be
'61 Plymouth full-size pushbuttons. All the pushbutton arrangements are different, using different buttons and fitting different bezels. I have a set of excellent '62 Dodge pushbuttons that won't fit in my dash no way, no how.
Though your transmission "was a known good unit with its converter",
was is a key word here. How long since it was driven daily? It's almost a lock that it needs a rebuild now. Even if you gave me the transmission and delivered it, I'm not willing to spend the money it takes to rebuild that 1-year-only nightmare, either in its original configuration or updated to more-modern internals (but you're absolutely stuck with the '65-only valve body, which is expensive to modify). No, if I were going to go automatic it would be an A518, but barring that I'd wait the year for the Imperial Services conversion kit just to have a transmission that's not packed end-to-end with suck (rear pump, no part-throttle kickdown, etc.)
Pushbuttons in the steering wheel were very cool, but Chrysler never did it to my knowledge. That was an Edsel thing ("TeleTouch Drive"... guaranteed you'll have the wrong number every time.

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