I have had a leg length discrepancy for over 40 years from a logging accident when I was young.
I have used multiple shoe repair / cobbler type services over the years with some being better than others.
American Healers has been Great to work with.
They have great turn around time and are very pleasant to talk to on the phone.
They often follow up with an email or call to make sure everything is good with the lift.
My lift is 1" thick, and they do a very nice job at making the lift blend in with the other shoe or sole.

Thanks!