Are you feeding the entirety of it to Claude (i guess)? Doesn't that eat pretty much all context - and considering that (AFAIK) the spec file has everything about the OS, doesn't available context space put some sort of "hard ceiling" to what you can add to the OS?
a. splitting it into sub-spec files that can be referenced. b. getting rid of it completely to prevent the LLM from hallucinating with potentially stale information.
256kb is the official minimum amount of RAM. 128KB should work but that's just going to let you run the kernel and some very basic built in apps.
Someone was even able to get it running on a PC Transporter on an Apple IIGS. One of these: https://68kmla.org/bb/threads/setting-up-a-pc-trasporter-on-...