As far as I am aware almost everything should work.
I believe the diameter of the encore tweeter is different, the older tweeter has eight screws in the face place the encore tweeter has just four. Also, I THINK the encore faceplate is a smaller than the older eight screw, AV123 tweeter. I’ve read that the newer tweeter is also a better performer.
Sounds like a fun project, if you’re able, grab some photos, I’d enjoy seeing the process and hearing your listening impressions of the update!
Enjoy!