there is a ton of myth & rumor , & I don`t feel right about suggesting swaps that could cause a problem , BUT 70-72 B body discs & 73 -75 A bdoy discs will swap with no problem , you Must swap the spindle to do this
Ehrenberg has a swap documented as well using B/E body spindle & using 75-78 rotors & caliper adapters to increase the rotor size by 1 " to almost 12" But 15 wheels Have to be used to do this swap