I can only hazard a guess - it might well be wrong, and I am sure an engineer will be a long.
The "problem" with after fit equipment is often that it has not been type approved by the manufacturer. This can mean the only way to fit a perfectly good item of equipment is to apply to the CAA for a minor mod. Obvioulsy this means parting with some additional cash and of course it must be a mod they will approve.
It would seem surprising if that aplies in your case.
Subject to the afore surely it would be possible to fit a blanking cover (simply a plate riveted to the back of the existing panel) with a suitable sized whole cut for the more modern AIs. You could even use it as an opportunity to fit a more reliable electric AI.