Do you have vacuum advance on the Nova?

If you've sourced it to ported vacuum, the advance mechanism won't add advance at idle.

The Camaro may have had the vacuum advance line sourced to manifold vacuum and if so, the carb's idle speed screw would be set for the idle increase due to the vacuum advance on this engine.

Try increasing the idle speed with the idle screw and adjust the mixture screws for the best engine vacuum as read by a vacuum gauge plugged into manifold vacuum.

As your mixture adjustment increases rpm you'll have to back off the idle speed screw to the rpm you want.