Back when I used GTR2, I developed a fondness for Vayline, Seven Hills, and Toban Raceway Park, and I know they were conversions from other sims. Generally, I'm not a fan of fantasy tracks, but I enjoyed these. They are available for AC as "direct conversions" with little improvement to bring them up to current standards for AC. Gilles sells his conversions of Vayline and Seven Hills, and considering that he was selling them for $2-3, I purchased them (and I identified a collision issue that he promptly fixed). The AC version of Toban seems to be pretty good, but needs work, and there's only one of the seven layouts it has in rFactor two.
If I can make time to work on them (and other AC projects I've started), I'd like to produce complete "remastered" versions of them, remodeling and improving the track surfaces (visible and mesh), "smoothing" a lot of the models that appear faceted, better trees, maybe more on the hillsides of Seven Hills, fix all the trees of Vayline, and more to increase the level of realism.
If you or anyone else wants to work on them, at least improving the road surfaces if you can, and provide a complete version of Toban with all the layouts, those would be great additions to the AC track library. Give these tracks a chance, mostly with lighter track cars, and you might enjoy them as much as I do.
For example, Seven Hills elevation changes are drastic, and a challenge to compensate for the surface changes in camber and undulations, but it's a rewarding little track to learn. If more character were added to this track with better, updated surrounding features, it could become a "gem" of a track for AC. Vayline already has a lot of character, but it lacks in quality that AC and CSP can deliver.
Just some thoughts, maybe beyond what you want to do, but any improvements to these tracks might be worth it.