Mazz - LFS has a 911. It's 100kg heavier and only puts out 360hp/288 lbft to what look like maybe 280-300 rear tires, but it's already pretty fun.

They don't have any official licenses, but the mechanics are there, under the bodywork. There's a car modifier app that you could use to edit this 911 into a GT2. You ought to give it a try. You can literally feel the suspension and tires working.
Latrobe - No free roam possible with the LFS engine. I think there was a Test Drive game recently, that ought to have that. You can try some of the "cruise" servers in LFS, but no guarantee they'll be free enough. You can start your own server or rent one and set it up for that, though. Password-protected and everything, so that only your friends could join and drive around. But the single-path restriction will prolly kill it for you, I reckon.