airride = 2 thumbs up
look at or for trucks with airride for ideas and possibly a used doner system, the easy way would be to install a used system from a truck with the same chassis as the one you have.
your other option would to be to install or fab a custom system, google airride, firestone and goodear ar the major bag manufacturers, ridewell and several other truck component suppliers specialize in suspension systems, look at what they offer and then choose a system that looks good to you.
the important thing with airride is the bag only holds the bus up, you have to have the necessary mchanical linkage to locate the axle front to back,side to side, and to counteract the torque of starting and stoping.