Well it turns out our own member H3NRY made schematics back in 1984 with MacDraw.

JDW has made a PDF of the schematics for modern viewing.

We're all very excited about your "Plus Too" project. And I'm sure most of us will be watching your site frequently for updates.

Edit: Oh, just found this topic discussing "128K Vs. 128k/512K Logicboards."