That should have a 26 inch radiator. As Ccas pointed out, you don’t have enough volume to keep the engine the same temp at cruise as you do at lower engine speeds.
The temp should not climb going down the highway. Perfect example of a radiator not doing its job.
I didn’t look at your links but as Brian pointed out, if that radiator has one of those flat shrouds on it, that is killing air flow at speed. Not good either.