Unfortunately, I just saw this post about the Torque Tube Eliminator. A friend of mine set his up with C-10 long trailing arms after putting in a '61 full size Buick pumpkin. It bolted right up and has the same axle spline as the '56. So, everything stayed, axles, housing, brakes rear sway bar, etc.
Both the Torque Tube Eliminator or C-10 set up will get the desired results. The only drawback is a lot of steel hanging down.