I think 500ks a day is optimistic. I have just travelled from Udapuir in Rajaakstan to Aramol in the northern part of Goa, its about 1350ks and took me 3 days of 10 unpleasant hours of hard riding a day and i dont think i hung about. Although i did lose a little time as my chain snapped twice.
I was chatting to another guy who did that same route and he took 6 days, although he was on an enfield!?!
The roads vary considerably and on very good sections with little traffic you probably could, if you had to, do 500ks, but others that are bad with bad traffic may limit you to more like 300ks per day, if you are lucky.
It all depends how you ride, but i would not reccommend to anyone to ride hard and fast in India for lond periods. It aint predictable or safe enough to do that.
Take it easy, enjoy the trip and arrive in one piece.
Some day so soon....