It is a matter of preference. It will work well either way. Originally it went to the air cleaner. This closes up the system and doesn't require a separate air filter.
On the '48 the original air cleaner and plumbing for the air cleaner were long gone - I recall that my Dad had an old "coffee pot" type air cleaner on the carburetor and one of the first repairs I had to make to the truck in 65 was to tap the body of the carburetor for bigger screws because the old air cleaner had shaken the top off of the carburetor.
When I restored the '48, it had a F-134 engine in it that I kept for a number of reasons that really don't matter here. In the end though, I needed an air cleaner so I scrounged around and found a reasonable facsimile that would mount in the depression on the fender well. That left me with the same issue you have - what to do with that pesky inlet on the oil filler tube.
I had a short stub of copper tubing welded to the side of the air cleaner and hooked up a short hose to the filler vent. It looks good, and who knows - WO just may have done something like that at some time or another.
(The sideways picture demon has struck again - but you can get the idea... just tilt your head).