If you are running an autocross event, you're just going to leave it on gear anyways. Especially with that monster motor. There are SoloII National Champs with V-8 sedans that run automatics.

On a fast road course with not a lot of slow tight parts and with that motor, not as big a deal as with other motors. Not 100% optimal, but it's not going to blow up and explode with an automatic.