Sounds like you have all the tools and experience required to tackle this project. Your '53 looks great!
I am not sure but the 4 speed may be a SM420 which is pretty straight forward to rebuild if it needs it, they are pretty robust.
Looking at your post about brake drums it is not clear which rear axle you have. I am guess a 1 ton would have the Eaton HO, probably with a 4.56 ratio although I believe some had a 5. something ratio. There is a lot if information about converting them to a 4.10 ratio but those are getting very hard to find.
