I agree with Cab... its time to start testing.. if this pump or the housing has a flaw you need
to find it.. we know based on what you said before.. the engine has had 2 pumps on it and
that didnt correct the issue... you tried changing the timing around and that didnt correct it..
its had a few radiators...if 440 had a pump or housing issue(I dont know sense I dont do
much on 440s) then maybe you need to check it.. as a check and your gauge accuracy with
thermocouples or another test item... this should be a start... and ask question before
you jump