Wilwood rear disc help.......

Just got around (could finally scrape enough $ together) to install my Wilwood rear disc kit. Bought the Moser housing & axle package (Trutrac, 33 spline) - upon installing the caliper, I notice that without any shims installed, the caliper can't center on the rotor (outboard pad is too tight). It appeared that the rotor wasn't sitting flat against the axle. Determined that the 3" studs were causing the interference. I verified by tapping the studs in a tad and was able to center the rotor with one shim. Not sure how to correct this properly. Moser only shows the 3" stud with the Mopar .685 knurl. I was going to go with the screw in studs but was advised by Moser that they may interfere with the internal parking brake mechanism. Should I "machine" (careful grinding) the stud or possibly open the rotor hole for clearance? Really at a loss & thought someone may have experienced this. Any help appreciated - as always.