Here's another suggestion: breaking it down further into steps, and taking the above into account

1/ Find a multi-sync 640x480 monitor cheap, say an old VGA NEC. Get your motherboard to output to that in greyscale/colour.

1.5/ See if you can stand Leopard at 640x480

2/ See if you can get that monitor and your video card/motherboard video to sync at the Classic scan rates.

Then you can proceed to the next step.

3/ Make up a buffer circuit to convert the analog video into binary TTL one bit black and white. Fast comparators, maybe. Test this on some other TTL monitor if you have access to one.

4/ Sync to Classic circuits. Mystery to me

Viola - 1-bit VGA

As for getting all this working with an OSx86 install (*snort*)