On the morning of the OP's flight, it is now showing J2C2D1I1Z1. With all the discount buckets available, I have to assume that the flight is no longer overbooked and that this was much ado about nothing. If it was truly overbooked at one point, Delta's load prediction algorithm seems to have been accurate. But OP, I look forward to your update.

If DL17 does somehow wind up oversold at the gate, VA2 is showing 7s in all fare classes in all cabins (as is DL6798, the codeshare on VA2), so worst case scenario is presumably getting rebooked on that flight.

OP, enjoy your time in Oz!