Tom one thing I thought I should mention. The rad seems to get enough air flow on my thirty nine buick. Actually by design the front end is similar to the Studebakers in some respects. Back in those days the front rails where closer together and the inner fenders where too.

I find with the 327 in the compartment there is not enough exit airflow. So it remains a little hotter under the hood than I would like. Causes no engine coolant system problems at all though.

Hopefully your vertical five cylinder engine is no more restrictive than the original one was to through airflow. . I think wrapping my headers or engineering some type of additional ventilation into the inner fenders when and if I get time would help in my case.

I guess I am just saying have a look down alongside the engine to see if there are good exit areas for the airflow. I do not know the comparative widths of the studabakers original engine and the Mercedes five cylinder engine. Again just a random thought that occurred to me.

Early thirty nine buicks had two design issues that had to be addressed. The early thirty nine grills had the teeth of the grill too close so the grill whistled. Also they eliminated the rear frame past the rear axel. This was a disaster. My thirty nine was a later in the year production so had neither issue. Your truck seems to be moving along well now.