You seem to have been racing for a while but I have NOT so, take this for what it's worth. One thing I can share with you about a .400 pro tree racing is the car needs to be tuned to get on the brake quickly. May take some carb tuning to get it right between squirters and pumps.
I have to run 0.015 in the delay box. I can red light on a .400 pro tree. I was mainly just wanting to know if people enjoy braket racing on a pro tree. We run the 6.00 class on a .400 pro tree.