Depending on how many miles you want to put on it, and even that's a small consideration, you can certainly run multi piece wheels and 20" tires as original, nothing really wrong with them.
More info here
https://www.stovebolt.com/techtips/wheels/

•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-