Here's the actual Gamba IIci ROM SIMM. I would like to have one of these, just to see how the SE/30 acts with and without various 030 and 040 accelerators. I found the IIsi and IIfx ROMs to have trouble with the Daystar Turbo 040 insofar as the internal floppy would stop reading/writing 1.4MB disks (although it could still handle 400k/800k disks just fine, and the Turbo 040 works fine with 1.4MB disks if the stock SE/30 ROM is used -- but the stock ROM prevents running of OS 7.6.1 or 8.1).
I also found this IIci Apple Developer Technote to be interesting. Figure 1-2 on page 7 of that PDF mentions the optional ROM SIMM can be anywhere from 0.5MB to 32MB in size!