If it was me doing this project, and I wanted to keep the dual tandems and run 53's on a Deuce.....
Lets pick a number, and just say that you want to seperate the axles by 6"
1- I'd lenghten all the dog-bones 3" each.
2- The bottom two leaf springs on the rear of a Deuce, that the axles ride on, is 52" I contact a spring shop and have them make four 58" long springs. Then I'd remove the two, top short springs in the pack, install the two, new longer springs to the bottom of the pack, against the original 52" leafs. Your axles would now ride on the new longer leafs, with the listalled lengthend dog-bones.
I don't think a spring shop would charge you all that much for four individual leaf springs, seeings how they don't even have rolled eyes on the ends for bushings, and they are all identical in length. It's a pretty straight foward, and simple job for them to make. Also with this setup, (removing two leafs and adding two leafs) your existing hardware (u-bolts and what not) would be able to be reused. So you would save some money there.
As for clearance, you'll have to ditch your J-pipe to run 53's on a Deuce. Even then the chance of rubbing the fenders is there yet, off road and in turns. I'd do a lift front and rear. I think, lifting the rear would be the simplest, just by adding another frame section under it.