A thread popped up on Rennlist recently regarding vacuum hoses on early cars. The following is not definative but it may help.
As an aside, the Y shaped venturi tube is shown in the photos. Some folks want to take this off, for reasons I am not sure of. It’s purpose is to provide a constant supply of vacuum to the brake booster, even at wide open throttle conditions, where there is very little manifold vacuum. Do yourself a favor that may save your life. Leave it in.