Hi Proper Job
Yes makes good sense to me to have outlet to low point and overflow to high point.
But seem to remember that overflow pipe went outside through hull.
Could this have been wrong in the first place has it came with the boat and I have had the boat 8 years.
The pipes and rads only ever got hot/warm 1/2 way down the boat depending on how high fire is.
The fire is a new morso squirrel 22 mm pipes, fire at front, header tank 1 gallon capacity open the atmosphere at back of boat and the boat is 60 feet.