I compared the schematics I've drawn a long time ago to the ones you've drawn - they don't match directly, so they may be derived from different versions of the HAPPY enhancement (or maybe one or the other was a pirated version, I'm not sure).
This is what my first version looked like:
The ROM contains the message "WORK COPY V1.1" in the unused area. Please find the ROM-dump down below.
These are the schematics I've drawn including information which traces to cut, the slow speed mod is also included:
For better understanding, I labeled the signals according to their function.
As 8k SRAMs became available, I modified the circuit to support a single SRAM chip (instead of two 2k SRAMs).
This is what it looked like:
and here are the schematics:
Most likely the signal A11_LATE is no longer needed in the 8k SRAM version. You may try at your own risk to leave out IC1D and IC1C and directly connect IC2 Pins 10 and 12 to A11.
Horry
HAPPY810.BIN