bleeding brakes
Like I said, tighten up the shoes. Tighten 'em up until you cannot turn the wheels, bleed the brakes, then back 'em off an equal amount on each side until they drag some. Stab the brakes a couple of times to make sure they are "seated." Adjust from there
ALSO CHECK are the rear cylinder sizes different between your old/ new axle? the larger the rear cylinder bores, the more "pedal" you will use up