1960 235 overheating questions

[nacho55]

Just seeing if anyone has some ideas (other than a head gasket replacement) for overheating on my 1960 inline 235
Little background, the truck was sitting since 1980something, so
Here's what has been done,
New fuel pump, fuel tank, rebuilt carb, new fuel line added inline fuel filter, New water pump, new thermostat, new radiator cap , & hoses.
It seems to run fine and idle in the driveway without getting warm, took it on the freeway and it stayed in the middle range of the gauge, soon as I exited the freeway the temp shot up and pegged it, I pulled to a gas station and let it cool of as steam was blowing into the overflow jug, added some more coolant and went on my way, got home and after it cooled enough I opened the cap and watched it run, and didn't see any bubbles so Im out of ideas.
It is running the stock fan, don't know if these trucks had a shroud from the factory, but mine doesn't,
Thanks for any input,