Caliper upgrade???

Being a disk brake car already, all you need is the bigger caliper bracket and the bigger disk.

you can get the larger pin or caliper bracket that already matches your caliper either being pin or slider type so you wouldn't need to change them just a bolt on upgrade... there are many write-ups here on FABO and FBBO if you search, I think there is even a sticky on the subject.

here's a thread I contributed what I could too: HELP! 11.75" Disc Conversion - Bearings, Seals Etc