The "anti-cavitation" (not mine) isn't for moving more coolant. At high speed the blades will form a "cavity" in the fluid & cause loss of flow (like a clogged snow-blower or lawnmower, still spinning but not throwing/cutting). The plate is a remedy, how well it works - I don't know.

Is the overheating a recent problem? What are the specs. of your 383 build, .060" over, etc.? Is your gauge accurate?