Mine T's into my breather setup, which is a bit odd. I have two 3/8ths hose barb exits from a plate covering the magneto hole. One goes to atmosphere via 3/8ths hose at the lip of the rear fender after going up to the vent being discussed. The other has a power brake check valve setup on it. Also have the intake valve cover vented to the rear fender. I run a Combat (2S) cam and it doesn't support a timed breather, so I shade tree engineered what I'm using now 30 years ago.
And where do P11 restoration builders run the other oil tank vent to? I'm not a restoration builder. I'm a tuner and tinkerer. My other vent goes into a Yellow plastic PlayDoh container with a hole in the lid. It just hangs there behind the transmission. It does get a little oil in it, and it's easy to empty.
I haven't spent a lot of time with the oil tank vents, but the vent pointing toward the rear is a PITA to plumb with 3/8ths hose. I used thin 3/8ths inch vacuum hose, but it still gets smashed down, since I'm lazily going over the flat stock crossmember oil tank mount and then under the frame above the battery box. Maybe someday I'll bend some brake line and do a better job.