510 is a very good DL. Especially from (and this is not an insult in any way, just noting a training difference) a BBer.
I think if you work at it, you will be surprised how fast 600 will come. A lot of people seem to make the jump to 600 from the low 5's very quickly. Please note that information is purely anecdotal; I have nothing to back it up other than my observations, and conversations with others.
One BBer I know changed from conventional to sumo once he hit 520 just to change things up and work different muscles. He had to drop weight but in a few months had it back up to his conventional numbers. I asked him if he feel that it helped, and he said it did, but never really quantified what exactly was helped, and not being a BBer I would have no idea.
Not to take the wind out of your sails, but I work out with a 17 year old 168 who pulls 630. I only mention that for the sake of it. Your 510 is still something to be proud of.
B-