You didn't read the whole thread, right?
I've got an almost perfect installation of High Sierra 10.13.6 running on my E6320. Eventually I will buy an older Optiplex to do my tests with Mojave. But at the moment I'm very happy with High Sierra
Btw, those random freezes seem to be gone since I upgraded RAM from 4 to 8 GB
I wouldn't recommend Mojave, it's unstable on my E6430. In particular it sometimes reboots after waking up, which is something that never happened on 10.12. It's already my second attempt to migrate, but it seems like I can't make it work.
Usually after download, the installation will start. You can just stop the installation without any ill effect.
You can then create an USB installer with the downloaded Mojave app.
(1) Create the USB installer via Terminal with "createinstallmedia" (a minimum of 16GB UFD is needed or an external USB drive)
sudo /Applications/Install\ macOS\ Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/"target_USB" --applicationpath /Applications/Install\ macOS\ Mojave.app --nointeraction
Note: target_USB = name of the USB drive you're writing to. When done, USB Drive will automatically renamed to "Install MacOS Mojave"
(2) Install Clover with following config, add appropriate Bootpack to /EFI/Clover
Install for UEFI booting only
Install Clover in the ESP
Install Clover Preference Pane
Finally add to Drivers64UEFI\HFSPlus.efi (not included in Clover installer)
Note2: The new format will be APFS, there's no way to use HFS+ unless you clone the drive to an HFS+ formatted drive.