I cant say for sure but I think just the shoes and wheel cylinders and drums are the only things different..not sure you can buy that lever spearately either,I dont recall seeing listings for those,just the spreader bar under the wheel cylinder..was probably "dealer only" when GM still sold them I bet..
Also the bigger shoes should be 11-5/32 x 2-3/4"..my van has that size in it now,I swapped a axle with 2.73's in it from a heavier GVW van ,my original one had 11 x2" brakes..