This conversion might be legit, apparently Rainmaker got permission from the guy who made the track for rF1, which in turn certainly wasn't a typical conversion from GPL, so I don't know why the first thread about it was pulled down from here. Maybe because it featured references to F1C forum and F1C mod, both of which seem to have a shoddy reputation here.
Anyway, about the track, the layout is good no doubt, it's the rest which is somewhat meh. There's abundance of photo and footage material from the most popular sections of Nords showing how these looked like in the '60s, so when I drove this AC version and saw legendary jumps at Brunnchen and Kesselchen missing (amongst the others), plus trees and bushes put where they shouldn't be (while others not being there), in some places it just doesn't look and feel like historic Nords at all.
So it's always a very subjective question of this or that track representation being "good enough", or not. For me this Nurby '65 falls into the latter category, but other's mileage may obviously vary.