It looks to me that your single line exterior pickup is at the very rear of a very long sump. Under hard braking, im betting the oil is running away from the pickup, in spite of the baffles. I would consider either a swinging pickup more in the center of the sump, or a swinging door in the sump, to allow rearward flow under accel, and block forward flow during decell.
Edit: that is a very long, far forward sump. Modified k-member?
