According to Andy Fisher of MicroAce, Sinclair’s 8K ROM and 16K RAM pack are completely compatible with MicroAce machines with minor modifications. Andy’s instructions:
For 8K ROM: Your MicroAce kit has 2 track cuts on board (both sides of pin 21 of ROM chip) and you made 2 links on the board. Before installing the new ROM, repair the cuts using a small piece of wire and remove both links. Cut the track going to pin 13 (data line 3) and the one going to pin 14 (data line 4) of the old ROM. With a small piece of wire, make a link between the sockets of pin 13 of the ROM chip (on the PCB) and pin 18 of U6. Also link pin 14 of the Rom chip and pin 3 of U6. Now plug the new ROM chip into its socket and apply power.
For 16K RAM: If you have a 1K MicroAce, the 16K RAM plugs in with no changes. If you have a 2K model, remove the extra 1K along with U17. Be sure that the 2.2K resistor in the place of R16 is installed! Now plug in the 16K module.