As far as vicosity vs temop. Drag motors don't gain a lot of oil temp. Mine seldom exceeds 160 with a diaper.
Doug
I was going to say something similar for drag race applications. I typically saw between 130-160F oil temp. And some days it took serious engine warm up to get the oil up to 130F.
At 140F, I am thinking a 10W-30 would be about 90 SUS.
At 200F, I am thinking a 20W-50 would be about 100 SUS.
IMO, Pretty close at associated operating temperatures.
And as previously posted, specific brands can vary from each other....