This isn't what you want, but it may prove to be of use to you. I'm not sure how janky the repackaging you did is, but installing from the original .run may be less janky, albeit more involved, and Nvidia has their Linux drivers back to 2003:
You can find instructions for installation here:
Take particular note, if you try this, of the requirement to upgrade Zorin's version of gcc. I'm not sure what 18 ships with, but 17.3 definitely ships with a version too old.
Pros:
- Total control over which driver version you use, as the .run is disconnected from any kind of update.
- Easier personal archival in case of... well, what you've run into already.
- Lower risk of packaging issues* (uncommon, but I've got a thread around here somewhere that no one could solve which turned out to be a packaging issue on Canonical's side) I'm basing this assertion on the simple fact that it's gone through fewer hands--fewer steps means fewer opportunities for failure.
Cons:
- Entirely manual. You can't just unmark and
sudo apt update. You'll have to get the new .run installer and go through the whole process each time. - Potentially worse integration with Zorin. I've had fewer problems since switching to Nvidia's .run packages, but even the Nvidia installer warns that distro provided packages may work better.
- Possible headaches if you're using a non-default kernel. (I have to jump through loopholes to use the .run package because I also use the Xanmod kernel. If you don't, this shouldn't apply.)
- No APT provided safety rails. The .run installers include an
--uninstallargument, but none of APT's features are available.
In the event that you try a .run installer, I STRONGLY recommend choosing the MIT/GPL license option when you get the choice between that and proprietary. I've had issues using the proprietary version with both the packaged drivers and .run installers.