Unless you’re using original NAPCO, Coleman, or otherwise period correct 4x4 parts that fit right and look appropriate I think you should stick with 2wd. Those front axles may have limited gear choices, making for a slow truck.
Otherwise as Ed point out it’s a lot of work and may not look that pleasing.

If the truck has been in the family for so long drastic changes may be a mistake, it’s only original once.

If you only swapped the rear axle for a 14 bolt you’d have faster gear choices and readily available Detroit locker, might get by with 2wd just fine. Read sticky thread about that swap.

•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-