I have a few suggestions:
1. ENR and most other trade magazines have plenty of ads for claim consultants. You could contact a few and ask for references.
2. Talk to the director of state AGC office to see who has been active in your state, they usually know who the contractors use for that service.
3. Talk to other government agencies that might have used a claims consultant such as your state's Department of Facility Management.
Just some ideas! I've never had to use one - so far.