I am running 4in marlins up front and love um with ranger springs in the back..I've have mazda springs in the rear and they worked fine as long as you run a toy overload and add about 2 to3 leaves..you said your framed was bobbed..if you run marlin or allpro spring in the rear you will have to relocate your spring hangers and you no longer have the frame to do that but you can always engineer a way to mount them
If it were me I would put 83 rears up front and mazda in the back....my brother runs the same setup with 38.5'sx14.50 sx's and he has no complaints
