Maybe I can help?
I've got 3 tunes I made that fit this event, maybe one of them can help you out.
Link to my garage is in my signature, just scroll down the page.
Honda
Mobil 1 NSX '01
Nissan
GT-R GT500 base model '08
Honda
HSV-010 GT Base Model '12
Of the 3, the HSV is the most useful, for this, and playing with the power limit hitting 600pp and even 650pp races.