Give me some time to think about it. I told a friend and he thinks he may be able to help me out. If that doesn't work I'll let you know. And thanks for offering.
Here is a pair I fixed with the method described. Not fantastic, but works very well. Both were missing chunks of scale where the pivot hole should have been.
Attachment 221339
I once worked in a cabinet shop. My work colleague was very very good at patching . He could make repairs invisible. I have tried quite a few times using his same techniques. Mine never really worked out as well. Apparently to be perfect and seamless requires quite a bit of practice. I'd say you are very close to getting this down pat.
Well my friend pulled through. I'll be getting two slabs 1x2x (1/8) in two weeks from a supplier in the states. For $80 I'm going to avoid destroying these.
There is an alternative if you want to use the original scales - use something thin but hardy as a backing piece. You can get G10 in 0.014" in various colours including white - I did this once on a set of bone scales and used a contrasting colour as the backer to make it look intentional.
I'm not suggesting you do that with your ivory scales - but a small piece of material on both sides, say in white, can be made almost un-noticeable.
if you could get a hold of some piano key ivory that might do the job for a reinforcement.