Chances are they do need to be reamed after they are pressed in.
Your best bet is to take the spindles with bushings installed, and the king pins, to an automotive machine shop and have them hone or ream them to size.

You will most likely have a difficult time with a brake cylinder hone.

Part of having a shop do it is they should ensure that the two bores have the same centerline. If you do them one at a time with a brake cylinder hone you can't ensure they have the same centerline. And if they don't then once you do get the pin to fit, the bushings will loosen up sooner than a properly reamed set.

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-