converting gp4 car to rFactor

I'm a fan of MDB Snakes cars (W300 etc.), but I'm not a huge fan of gp4. So I'm gonna ask me now, how I can convert a car from gp4 to rFactor? It will be only for my personal use, cause the project what I have planned isn't interesting for others, cause it's only a fictional set.

Good luck, back in the day I was trying to get the W300 and then the main series converted... Mini_Maestro was doing it but stopped and no one else tried.