Couple of points here..
First off, the #27 car, (the second Andretti Green one), will be driven in the GP3v1.13 set by Dario Franchitti, although the carset will come with helmets for all the alternate drivers. In the GP3-2000 set, it will be driven by Dario, Robby Gordon, (Indy only) and Bryan Herta - Dario will get to drive at Motegi, as Dan Wheldon has a full season of racing in my carset! Aslo, Michael won't retire at Indy, but will see out the season.
Second, building an oval isn't as simple as it should be. GP3 is designed for left-hand banking and, as ovals have right-hand banking, the track doesn't rise up, it slopes down to the left! I intend to work on some IRL ovals over the winter, but I want to crack this issue before I release any. once I've cracked it, it should be (relatively) straightforward to reverse engineer the F1 course from GP3-2000 to use the jams and objects to make indy with 4 corners. But don't hold your breath.