When I got my 66 pagoda it had "Armstrong Steering" and I ended up buying a complete 1967 250se taking the steering box, pump, pulleys and brackets from that sedan, changing it over to my roadster, reinstalling the manual steering parts into the sedan and reselling the 250se without P/S for more than I paid for it.
The fuel injected 6cyl. 108 series (66-72) was the latest car that used the steering components that fit on a Pagoda, the steering box and pump can come from a carbureted model, but the brackets for the pump and tank will need to come off an injected motor. 111 fin tail cars (60-68) also have steering parts that will fit, but most of them had manual steering. The 114 series (68-76) cars used completely different steering components and will not fit.
I did the change-over nearly 30 years ago, so I don't have any really good details on the process, but I remember that the manual steering shaft inside the column is about 1-1/2" longer than the one for P/S.
The sedan column was not usable in the Pagoda either. I imagine I ended up cutting off the shaft and machining one end somehow to make it fit. Otherwise you will need to find a 67 or earlier 113 steering shaft. All the other parts are a direct bolt on, from the sedan onto the roadster.