You could add it with the original steering box but it's not a very desirable system any more. It uses a sensing valve in the drag-link, and a hydraulic cylinder between the axle and tie-rod.
This system was used on GM cars as an option in the mid 50's, I think someone sells parts or reproduces them if you really want to go that way.

I would opt for a steering gearbox swap, and cut off the original steering column so you can reuse it.
You do not need to change the entire front end, just the steering gear box.
Does anyone sell a PS conversion kit for your model truck? I'm only familiar with the AD years.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-