I just switched back to Hagerty from American Collectors because they wouldn't cover the '66 when I wanted to add it.
I didn't check with Grundy, but a good portion of these classic car insurance companies won't even consider covering a 99% street car that makes a periodic trip down the 1/4 mile. Sucks that you basically have to lie to them if you ever plan on making a "fun run" at a local drag strip.