Page 2 halfway down is recent info. Holley is still a week away from having correct part.
https://cccforum.discoursehosting.net/t/location-east-coast-nos-and-used-cougar-parts/67/1
For the PVC “regulator” any part store carries them.
The grommet/gasket that the regulator sits in is another story. Sizing on all I found was wrong; as was the external shape.