Well that bike would be the exact same as a 600cc SS through state farm as they would both be listed as a 600cc regardless of style.
I am assumimg you are under 25 or not bring a car to state farm to get that quote as I pay 70/month for full coverage on a 600 SS through SF with a multi-vehicle discount.
I'm actually 31. Maybe TD is lower because I've also got my house and car insurance with them. Regardless, I am with M2 license which I haven't had for a long time, perhaps that's why the quotes are so high...