Well they are so similar that it hardly requires much conversion.
Just check out a track that is both in GTr2 and Race 07 and compare them.
Like Monza or Brno.
And if you got a tutorial how to convert Gtr2 to race 07 already then the stuff is already mentioned.
You do not even need to convert the gmt's in 3Dsimed to get the tracks running in Gtr2.
Just a little time and a text editor.
Unless it is an original Race 07 track where you do need to change some shader settings.