I've done most of the changes that cool down these V-8's in a run hot condition. All but the masticated fillers and the divider plate clearance (.060). Most would think my convertible runs hot at 210° - 235° peaking at 245°. But it runs just fine on a hot day, in a slow rolling parking lot (Woodward Cruise).

I think you're chasing the dragon that haunts us all. Unless your experiencing boil over, I wouldn't throw anymore money at it.