62 C30 Rear Suspension Question

[ElReeso]

So I got a 62 C30 Dually with an Utility Body on it.

I´d like to lower it and I´ll go with a 83 Front Suspension. That way i´m getting rid of the Torsion Bars.

Now to the rear.. its a Dually Axle with Leaf Springs.
Is there anykind of Flip Kit or Bag Kit for Dually axles? All I can find is for the single wheel application.
I´d like to either lower it around 5-7" or get a bag kit

Thanks in advance