There are PAK68/2 and PAK68/3 schematics on the internet someplace. I’ve seen them before but it appears the links have all gone stale. I have a scanned version of the original PAK68/2 article in the C’T Projekt (in German). Apparently there was a FRAK/2 circuit as well which added DRAM to the 68000 socket.
Thanks and have a nice day!