First rule of tuning a car is, there's many ways to skin a cat
Based on what I'm seeing here (not yet driven your setup yet) I would start by turning down the dampers extension to 40 front and back. Having this too strong can add more body roll and weight transfer that could amplify any oversteer.
Try 35 front damper compression and 30 rear damper compression. This helps tame oversteery cars the best imo, or atleast a great way to start.
Moving to the drivetrain, in GT games, I find having them all turned down to 5 typically smoothes out the car and can help settle it down, I don't know how else to explain it. While doing that will give you less acceleration, you can circle back to this after the rest of the tune is done and increase the Accel. Sens. up 5 notches at a time or so until the car seems to drive unstable again.
For me, one of the biggest causes of oversteer is front toe, while it can help the car turn in better, it can also introduce oversteer at the beginning of the turn, so try it as 0.0 up to 0.5 (I'd suggest 0.0).
The spring rate is a little offset, with the rear being stronger that will induce oversteer, so try kicking that down to 2.8 or so and leave the front where it is. I dont know where on theslider these numbers are, but for oversteery cars, softer-to-medium is typically better.
Next, the sway bars are a bit high, that too will cause the car to react quicker and give more weight transfer, try setting it to 5 on the front and 4 in the back.
Ride height, I'd say for this car try putting front and back right in the middle of the slider, then maybe drop the rear 5 ticks if you want. By giving the car some more height and 'range' it can soften the oversteer tendencies a bit.
The downforce plays a huge role in tuning cars as it can basically override any adjustments you make, or be a one stop shop for fixing oversteery cars. The trade off is top speed and acceleration in a straight line. So for tracks like Fuji, don't be fooled into increasing your cars rear wing and calling it a day, you'll end up losing along that front straight. However, for Suzuka, you could run rear wing for days.
HTH a bit, I'll try and get a tune going for her today/tomorrow.
Jerome
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Yeah, the PP doesn't make sense and is really why I just leave things stock-ish 
