Look for a local "Metallurgical Testing Service". There is typically a service such as this near most large cities, though you might have send your sample some distance. I'd dig for a "racing experienced" service in the Charlotte, NC area, such as:
Metallurgical Technologies, Inc in Mooresville, NC.
OR, if you want to find something closer to home, you can check on ThomasNet.com, the online version of the Thomas Register.https://www.thomasnet.com/south-carolina/metallurgical-testing-services-84848597-1.html
It is a relatively simple matter for a professional testing service to determine:
heat treat specification
and whether or not these were "properly" accomplished
Ask for an estimate of charges in advance of sending in a sample. It can be pricey . . . . .
Do NOT expect the sample to be returned in a usable fashion, as this is "destructive" testing. Basically, they are "reverse-engineering" the part. These places can also perform "non-destructive" testing, but it is not as certain.
Additionally, a metallurgical professional can suggest alternate materials and heat treatment specifications. Those might perform better, but the person specifying needs to thoroughly understand the nature of the usage. And be aware that "better performing" may also be "higher cost".