You might be able to upgrade the transmission. I am not sure if you can do it to your vintage truck but the '48 and up can be upgraded using a T-5 transmission with O/D. You can do a search of T5 transmissions, there's a lot of information out there. One note, the T5 is not as strong of a transmission as the stock one in your truck but as long as you are not planning to haul heavy loads, which your truck was made to do, you should be fine with a T5 especially if you can find a T5 World Class. You could also try the transmission from a '87 and up three speed with O/D.
Just another option you can check into. Like Stu said, check out the FTE site. Also the Ford Barn site. There is also a guy on the Bonus Built site, '48-52 Ford trucks, that is using a T5 in his F-5 truck.