I still own my Superboard (8K RAM) which I mounted into a wooden case I built and also sold back in the late 70's. Anyone remember "Dee Products"? That was me.
I'm trying to fix up the same 600 Rev B board and running into the basic load error as well do you remember what the fix was for you? I have tried replacing the basic (1-3 and 1-4) and monitor rom along with a cpu swap
Maybe an issue with Chip enable logic for the ROMs. Do you have access to an oscilloscope or even a logic probe? I would also try running the machine up with the minimum amount of memory installed or 1K. With just two 2114 you should get 255bytes for BASIC, I think. Also check out the OSIWEB forum.
