The Gen6 race was much more eventful than the RUF race for sure. Lots of drafting, lots of rubbing, lots of crashing. I'd champion a Bombcar (or new series) involving that car with fixed setups on big ovals (and Dover/Bristol for good measure). Or something slightly slower but a bit more manageable. Holding the line in a draft with this car is exciting/scary.
I'm down for Motegi too. I don't own it yet in iRacing but I liked it in Forza and LOVED it in Ferrari F355 Challenge. The oval configuration probably won't be half as good as my memory of racing it in that game, but I'd still be willing to toss some money at iRacing to try it out.