Does anyone think it is the radiator besides me?

A few things will make them overheat at speed.

A collapsing lower radiator hose. The water pump just sucks it flat at higher engine speeds. If the engine cools right off when you idle, then look at the lower hose. Rev the engine in neutral & watch the hose. Stand clear of the fan.

Retarded timing will also make an engine run hot. A stuck mechanical advance or failed vacuum advance will raise the operating temperature at higher speeds. Retarded timing will not "ping" even when hot. A timing light should be enough to tell if things are working.

Lean running conditions will raise engine temperature. A partially clogged fuel filter, or tired fuel pump may seem fine around town. At 70 mph it can lean things down quite a bit. How do the plugs look after a highway run?

The airflow through that radiator was just fine in 1965. We drove those cars up steep grades at WOT without issue when they were nearly new. Check the basics first before you start throwing parts at it.

B.