Anything Chevy because their cheaper to build, more plentiful, more reliable, easier to work on etc, etc.
Plus and you won't feel like a black sheep or the lone ranger when you pull up at the track. You'll get more help and ideas from fellow racers with a Chevy too.
Keep the GTX, it might just be a good IRA choice later.
Now is the time to buy, don't wait till racing season starts, everybody and their mother is selling a racecar now.
Goodluck, Charles