Just wondering if are you using a keyboard and mouse on the Holley dash to set them up? I know a wireless mouse makes setting up the gauges much faster on the dash instead of using the touch screen.
Also, a downloadable Holley 12.3" or 6.86" dash file for a GN is located on my web site click
HERE. If you prefer to use Googe Drive to download them, click
HERE. It will set up the gauges for you. Just be sure to check the gauge settings for YOUR car so they will read correct. They were set up using a Dominator ECU.