78 pontiac T/A with 400 big block, running too hot.?

[B-mash]

i have a 78 t/a with a 400 big block , last year it started barking when it would kick down in passing gear, it got worse as time progressed. so i had it looked at and worked on by a few people, and before you know it we had to throw in a new cam and crank i think from overheating, now the car runs but wants to run hot.i put a hi flow thermostat plus water wetter treatment to keep it cool enough to run. ive had this motor out three times to look it over, but cant find anything. would like to know if it is the cam or what. I have also replaced the carburetor, checked timing, checked all vacuum lines, and replaced the the whole rotor assembly. I need ideas as to what else could possibly be causing it to run too hot.