07C4S

I have a classic car that was hit back in October after a full restoration and a few hundred miles. Other driver admitted fault and their insurance company paid close to $20K to have the car fixed. It's now done....but I need to proceed with a diminished value claim. Has anybody here had any luck with appraisers or even a lawyer that specializes in this. I'm located in Chicago and it's likely every state varies so posting this here hoping someone has some local leads. Thanks!