It took a few hours to research and get a custom ROM installed (SmoothROM v5.1), so I was dismayed to see that it lacked 3G support. Oops. So I started over again using Nexus Root Toolkit and pushed the latest cyanogenmod nightly for Tilapia (Nexus 7 3g) and gapps via my laptop. Success!
cyanogenmod is kind of boring because it’s so stable – and that’s a good thing.
Regarding the title above,
grouper = Nexus 7 wifi
tilapia = Nexus 7 3g