My thoughts:
Excessive windage in the rotating parts, which could aerate the fluid. The normal fill is about the bottom of the valve body, so it doesn't take much higher to reach the rotating parts. And aerated fluid could be bad news.

1993 Daytona, 5.50 at 130mph (1/8) 1.19 sixty ft (PG). Link to 572 B1 - Part 1