It looks like you got it handled which is good. for what little it's worth, if the items that are currently on your car are larger than stock I might be inclined to go with that size. Bigger shoes and drums = better braking which I'm a fan of. Carroll Shelby was a fan of larger brakes on the rear of his cars as well, so much so he used station wagon rear brakes on them. Ford Motor company sometimes(not always) ran larger back brakes on Mustangs as well if they were heavier models like convertibles.
One final thought, if for some reason your car has a different size than stock backing plate and you go with narrower shoes and drums.Once the drum is against the axle hub,you may leave the inboard side of the brakes open to the elements and such.