I guess some of the confusing parts on the Holley website is because of a different methodology than I would employ. Stuff that is generic and fits multiple years and models doesn’t show up using the filters. Other parts, like motor mounts are part of a kit in the filtering, but the motor mounts themselves aren’t listed unless you open the kit page and then they are shown (e.g. kit contains…with links).
So it seems they haven’t dropped anything, they just have to be searched out if you need them.
And the issues with headers is completely the EPA.