Flathead oil gallery

[m606paz]

Hi Boys!
I have doubts about the lubrication galleries in my flathead, since I am not going to disassemble this engine now.
The motor has a hole with horizontal outlet pressure, with outlet to the left. Then there is a hole in the middle, with vertical outlet, to install the oil pressure sending unit. Those last two communicate.
There is a third hole that we normally see covered with a plug, but in my case, it was the oil filter return.
There is no communication between outlet and return holes...
Does this last return hole need oil pressure?
My engine no have valve relief.... is a 1944 model.
Thanks in advance!

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