Hi wanting to change from drums to discs on the rear . I bought empi vw disc setup years ago but calipers would never work . So i was wondering if i could still use the discs that came with the kit and use a different caliper e.g subaru or ford and use a different bracket ?

They need power bleeding to work correctly, If you change the disc you will have to match the caliper to the rotor thickness and fabricate the bracket, also an engineer will be required to certify the set up and pass a brake test, I am on my third set up i have made and am currently building a front set for my new build.