Rear Drum to Disc Conversion Question

Most rear calipers have a helical drive to account for brake adjustment, this is why you thread the piston into the caliper when changing pads and not push them in with a clamp. The parking brake adjust pad engagement so if you plan to not use a cable ever so often crawl under and move the lever. I'd just hook up the parking brake because that is the safest thing to do and it will adjust the caliper with no worries.