I had a bit of struggle getting High Sierra to install on the 7010, apparently to small EFI partition coming from Windows (you need at bare minimun 200mb) I don´t know if i solved the issue the right way.
My method was to clean the drive using diskpart then convert to GPT. "Create partition primary" then shrink it (i used 400mb) and then "create partition EFI". The installer works and you can proceed installing High Sierra. The problems is the next step when your in MacOS the first time and want to install Clover (standalone or via Multibeast) your EFI partition is in NTFS and you can´t use that for clover boot loader. And you get an error trying either way. I found a old post on how to via terminal in macOS format the the EFI partition to fat32. Here are the part i´m uncertain about, mixing format might not be optimal... But it works. And you can proceed installing Clover after the format. But you have to do this standalone the first time (i did it via Clover configurator) Then you can use multibeast.
I dowloaded the DSDT and kext-pack for Dell optiplex 9010 (same machine Sandy bridge instead of Ivy bridge) googled all kext and tried to find High Sierra working ones, or at least Sierra. Skipped a few that seemed obsolete and used kextbeast, then repaired permission via latest kext utility (approved on Sierra) I used the original kext for audio (2.8 Voodoo) and a support kext for that from the 9010 folder.
The DSDT and SSDT from that folder won't work out of the box, in fact it shut down the boot in matters of seconds if i put them in EFI clover folder. Someone should probably edit them for more recent macOS...
Sleep won't work, there seems to be new powermanagement.kex (nov 2017) and i will try that later this day. Haven't tried imessage yet, one thing at the time.
I will try to update this post with links to my sources later on.
Dell Optiplex 7010 SFF
i7 3770s
8GB ram
GTX 1050ti
I tried the recommended "iMac 13,2" but it won't let me boot. 14,2 works out of the box (Haswell).