another 360/408 over heating

I remember buying a brand new 340 radiator and all that crap when I got my 340 going 20 something years ago and and it would overheat eventually...

What is the initial timing and full Advance timing? Let's say the timing is perfect just to give you a little info here , Does it overheat driving down the freeway for that entire time ..? ...or is it only overheating when you sit at an idle?
If it's only overheating when you sit at an idle you don't have enough fan n that fan shrouds a piece of **** ..so you'd need to put A real fan/s on it. If it overheats while driving down the highway...you have two things going on ... either wrong timing and detonation...or clogged/too small radiator, too lean/ too rich..blown head gasket worst case.