Used Sniki's guide, with Mojave. Was having trouble again with the High Sierra USB installing (kept getting error message about loading resources for OS). Couldn't get it to boot with iMac 13,2 SMBIOS revisions that work fine with this guide and High Sierra, used Mac Mini and got it to boot. Sound works with Sniki's guide, haven't tried front ports yet.
So I have two installs, on separate SSDs, watching console messages and such to see which one is more stable. Mojave via Sniki certainly boots faster. Still no PCI port function though (PCIe works fine).