Question...what is the normal running temp for a 1972 340

What is Diagnosis ?
Everyone keeps saying ...Bigger Radiator ....If I buy one I plan on at least trying to get a bigger 3 core, but I keep asking myself ......surely it was not running hot in 1972 with the original 2 core. I have had the car for 16 years used to drive it to the Nationals 10 + years ago .. about 4 hours from my house, 55-60 mph on highway, after about 3 hours would always notice it leaning to the hotter side.... nothing to scare me, I just blamed it on the 391 gears. I started trailering to Columbus, the short 30-40 minutes from hotel to show never noticed anything.
Last year I drove it back to Indy for a Good Guys show and the following weekend to Monster Mopar again 55-60 with 323, gears took my time ....again it ran a little on the hot side enough to make me a little nervous this time .......now I cannot seem to drive 45 min. at 55 and driving 65 70 for 10-15 min puts the temp gauge up to 230-240 before I get off the highway and it starts cooling down. Looks like Radiator is next ......after that I guess Ill pull the motor knock out all freeze plugs and have a look around.