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You could put in a T5. Or there are tailshaft OD units made by a couple different manufacturers, but I wonder how long you'll be happy with a non syncro tranny on the street.
If you are talking about the Borg-Warner OD that was used on cars and on F-1's from 53-on, I don't think it would work for you. First of all, it wasn't designed for something as heavy as your F-3. Second, as far as I know, it was never used with the HD 4-sp, so there wouldn't be any mainshafts with the proper modifications to mate with the OD.
If you are going to use your F-3 as a truck, and haul stuff up to its GVW, you should probably look for a modern Ford 5-sp. If using the T-5, you'd want the World Class model for its greater strength. On the other hand, fully loaded, I doubt the 8BA is going to pull an OD ratio. That's one reason it doesn't have one!