To be honest. I would look at purchasing an IRS differential kit. Beautiful kit and this would allow you to run different wheel brands. I've noticed most guys doing this here in Japan.
Upper arms are the same.
Steering blocks are the same.
Rear shock? You mean the middle damper? Or the pitching damper?
Lower arms are different. You might need to buy a new lower chassis. For it to work. I would save you cash and wait for the new chassis to come out.