[ole yellar 50]

Strange, but thru all of the causes for flathead "overheating", I have never seen any mention of the bottom radiator hoses collapsing at higher engine RPM.
Ford bottom hoses used to be made with a thick walled material AND also included an internal spring that prevented the hoses from being sucked closed by the water pumps. Hoses supplied today are much thinner and do not include the spring.
It's very easy to check if hose collapse is occurring: just raise your hood and rev. up the engine to around 2000 rpm while watching the hose. If they collapse, there's is your overheating cause.