The only Mopar cooling problems I've had, once all systems were clean and working properly, were cars that had the OEM radiator changed with an inferior replacement or recored with a cheap core.

Most of the replacement cores and radiators have a low fin count and fewer tubes than the OEM units. Pay extra for the good stuff if you want a cool running motor. A core with 1 or 2 extra rows may be needed if the motor is modified, otherwise the OEM count should work on near stock motors. BTW, I've never seen a 3 or 4 core radiator, radiators have 1 core with 2, 3 or 4 rows.

My '70 440-6 Bee runs cool with the OEM 22" radiator in the summer here in FL, were as my 225 slant six '68 Signet with a 19" replacement tends to heat up at highway speeds.

How good were the OEM units when new? Even the 440-6 C bodies came with a 22" radiator!