After I got four W65c02-10 I tested them all on the breadboard.
Everytime I had stability issues with my LC64 on the breadboard I changed the WDC CPU to the Rockwell - and all is OK!
- The WDC is not TTL/NMOS-compatible
- W65c02 has a more critical timing - it's for 10 MHz.
But the WDC runs not stable in the system and I decided to use the good old Rockwell and adress-buffers with OE. The Rockwell 4MHz CPU runs without any problems @ 5 MHz - that's enough for me and the fast 90ns-eprom.