FWIW, I had a mix-n-match of Indy and ARP studs w/ my Stage VI heads: you need to verify the UNthreaded portion of the Indy studs that protrudes through the shaft hold-downs doesn't end up above the top of the hold-downs. If I didn't have some fairly thick shims stacked under my shafts because of rocker geometry "fixes", I would have needed to add extra washers under the nuts that retain the shafts because of this.