It is possible to upgrade the old 16Mbit (320 2.8cc) SWC to 32Mbit - a friend of mine did his back in the old SNES days. Fortunately, he still has the unit and I'm in the process of getting digital photos of the chips/motherboard to post here.
He says he used 1Mb 30pin SIMM PC memory modules for the chips but I'll hopefully verify this once I have the chip serials.