The radiator you sourced was brand new? Two engines acting exactly the same raises questions unless as mentioned your experience is normal and typical on these.

You can wire in a switch to separatly manually activate the electric fan system. Especially if there is no normal temperature switch that does it when you think it should.

You have a clutch fan and should also check that it is in tip top condition. They are and where a wear item on each of the engines.

Since you did change out engines the fan shroud is present now? Verification of the dash temperature gauge may not be a bad ideal as well. Even though it is probably overkill to do it.

If your fuel milage is lower than normal check for a dragging caliper or two as well. This could make the engine work harder than it should have to. Just feel the temperature of all the wheels after a run for sameness of temperature with your hand or a laser temperature reader. This is how I determine if a caliper needs attention if it is not obvious.