Bringing this thread back to the top.
Haven't made any progress on the swap...
However I have been thinking about it a lot and decided that making spacers for the backing plates to move them out and allow for mounting the original drums outboard of the hub is pretty simple and not a bad solution. This will give plenty of room for U-bolts between the spring and backing plates.
A more expensive version of that is buy single wheel brake drums of the same shoe width and diameter, then make and weld new backing plate mounting flanges in the appropriate spot on the axle (use original backing plates/brakes). If you already had to buy new drums this is the cleaner approach. Because of the distance the backing plate moves it's probably not a good idea to make a simple spacer.... it should be welded in place.
Grigg
