No, 500 would not be equivalent to a 30. 125 is going to be the midpoint on each section - basically, it's a 14 point scale, spread over some funky interval instead of just 1-14. So a 125 in any section would essentially be a 7, which to my mind should be equivalent to a 7 or 8 on the current MCAT. So a 500 would equate more to a 21-24ish.
I do feel badly for the first batch or two of pre-meds applying with this scale, as they'll have to try to equate that back to the old scores to figure out where they are a good fit for applying (unless AAMC does some sort of scale conversion for the MSAR).