Honda CB350 is leaking oil from the fins on the left side head?

It's not the head gasket itself but a leaky O-ring at the cylinder head gasket level of the oil pressure lines to the camshaft. So I don't think there is a useful fix from outside, maybe one can plug in something between the fins to make the oil go elsewhere, but that won't stop the leak. Oil loss however should be negligible, if you have considerable oil consumption, this is probably burning of oil.

The O-ring sits between head and cylinders. There is a cut-out in the head gasket for it. If the head gasket remains intact during getting off the head, one even may just swap the O-rings and leave the head gasket in place.

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It is leaking between the head and cylinder = > on the left side.   Does not leak much, just enough to get the fins on = > #1 cylinder oiling and maybe some oil blow underneath on a long ride.  I = > have been told that these bikes or notorious for this.   Is it a major = > deal to repair?   I assume no stop leak can not be used.

the solution for this:-----------

There is an upgraded head gasket kit available that will take care of the problem. The leak is around the "knock pin" (alignment dowel pin) at the oil passage from the cylinder to cylinder head interface. The new style gasket incorporates a rubber seal that does a better job of sealing as the parts expand and contract. 

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The leak is probably comming from the little rubber disks that seal
the holes for the 10mm bolts that hold the head to the cylinders.They
are found under the camshaft bearing carriers. Remove engine from
frame,remove valve cover,remove camshaft and bearing carriers and
your there.Or just keep cleaning the engine till you need to pull the
engine for a more serious problem.

just pull the cam on my motor,
The rubber disks (seals)will be quite hard. Basically, Honda put four large
holes (apx 1”) down the middle of the head near each spark plug.
They then used a rubber disk which is held in place by the cam holder
to form a seal to prevent oil from leaking into that cavity. Before
you go too far, try taking the spark plug out, get a small mirror
(like one a dentist uses) and try to look at the spot above the spark
plug hole. You should be able to see if the seal is leaking. The only other known leak is the tach drive seal. It’s been known to go bad and
oil can leak down onto the fins from it.