Poor Radiator floor- Help

[REByar]

Hi,

After trying many of the suggestions to correct my overheating problem I am down to the answer may be that my radiator is plugged. I have a 1930-1931 radiator. I run water thru it and it runs clean( have used many of the cleaners recommended here). I am looking for a shop in my area, up-state South Carolina, that can rod the radiator. Any suggestions? The other question I have is that I can look down the radiator spout and see the core. Is that normal? Many pictures show a baffle which to me would prevent you from seeing the core. I did try and put a thin wire down a few of the tubes and did not find any blockages. But I can only reach the tubes in that 2" area.
What I mean by overheating is that after driving for 30min at speeds of 40mph to 45mph the water starts to boil at the top of the radiator and runs out of the overflow tube. There is no steam coming from the top. I can drive for 30 to 45 min under 40mph and have no problem. I added a thermostat and that just made it overheat faster.
Any suggestions would be greatly appreciated.
Thanks
Randy