340 overheating problem

When I troubleshoot overheats, I always start with a gutted t-stat, straight water, and a mechanical fan. With a gutted stat its also possible to check water circulation by observing it through the filler neck when the water is cold. I have moved my cam timing around from 3*retard to 4* advance with no appreciable change in running temps. Granted my current engine is only about 430hp..... I run a 26in factoryA/C rad, a Milodon hi-flo pump, a hi-flo stat, expansion tank and a 7-blade clutch fan.And the hood/cowl seals are in. And fresh air. Works for me.