If you have a dremel and 45 minutes to spare, you can fit just about any AK trigger in the Ace. I know because I did it after giving up hope on a restock of the Galil specific ALG AKT.
Specifically, I can confirm that the following triggers can be modified (slightly) to fit the Ace:
(1) ALG AKT-EL (personal favorite)
(2) ALG AKT-UL (too light)
(3) B.A.D. EKG (just okay)
(4) Elf AK SE (additional modifications required)
(5) Power Customs Adjustable (runner-up)
If you want a two-stage trigger, the only option I've come across is the Power Customs Adjustable Trigger ($89.99 at Midway). The trigger has adjustments for overtravel, pretravel, disconnector engagement, and trigger pull. And with some patience, you can dial-in a really nice two-stage pull (mine was setup with a 2lb first stage and ~1.8lb second stage).
As to the required modifications, see the below photo. If you have any questions, feel free to reach out.
https://i.ibb.co/x8F51zk/Power-Custom-AK-Trigger-Galil-Ace-Modifications.jpg