Going back to the original stuff probably will help him somewhat.

It runs OK at idle when the air is being pulled through from the backside of the radiator, not being pushed through the condenser.

It heats up at speed.

Aluminum radiators like more airflow than copper/brass.

He has a very restrictive condenser and cooler in front of the radiator.

The aluminum radiator is going to be quite a bit more hurt by the airflow restriction than the copper/ brass one, so it should get better going back.

The best solution is to get rid of the condenser and use the aluminum radiator with good airflow.