This is a trev_ham replica board.
I have wired the cassette lines to side-B of the backplane as follows:
IC2 pin 16 (PA7) to B19 (CASIN)
IC2 pin 17 (PA6) to B20 (CASOUT)
IC2 pin 18 (PA5) to B23 (NHITONE)
This wiring is not quite standard, see details here.
The only other important thing to remember is to fit the link where the regulator should go to feed BLK0 to the backplane otherwise many cards like the VDU will not work.
Front Panel Drilling