At our shop we have made ball bearing fan hubs, the first one for my own '47. The oil reservoir hub was not one of Ford's Better Ideas". After two hubs began to fail, we designed and built the first hub. The original does not have bearings or bushings. It depends on an oil film to prevent self destruction, usually from over tightening the belt. The two sealed ball bearings in my car's new hub have lasted over 25 years. We get $395 each, which is cheap, when compared to replacing a ruined radiator when the fan goes into it.
1948F1Pickup has the best solution. In 1999 I also made a custom pulley with really heavy duty bearings and never had to worry about that fan hub again. I think DRAKE also sells them at a fair price. The price of a chunk of 6061 aluminum makes buying "one done" a better move. You can also make spacers to fine tune fan location.
The shaft is heat treated and pretty darn hard. Usually the part that wears is the spindle bearing (21A-8626) which we reproduced. This should snug up the fit for you. We also stock the two paper gaskets.
This link will tell you all about this fan assembly. Yes, it’s a pretty crude (simple) design but it works quite well as long as you remember to lubricate it per the factory instructions.
http://www.vanpeltsales.com/FH_web/flathead_oilfilledfan-servicetips.htm