I thought that 1MB of RAM was/is a little low. Therefore I searched the internet for an affordable 4MB (or bigger) RAM card. I found one made by GGLabs and they also offer(ed) bare PCBs.
I ordered two bare PCBs and went searching the internet for the 74xxx logic chips, together with the 20-pin SIP RAM modules which are supported for this card. I found these through AliExpress.

Unfortunately I wasn’t able to find the resistor arrays which GGLabs originally used, but using (small) generic resistors also worked.


4MB RAM card for the IIgs from GGLabs

The RAM card is corectly identified. I did a burn-in test using the Sirius image (from the old sector16.com site) for at least 48 hours and everything was/is still fine.


IIgs CDA showing available RAM

Right now I have 2 4MB RAM cards, one for each of my IIgs.