Basically the fins are there to wick heat away from the head and the Puch head was designed for a horizontal cylinder so that's why the fins radiate out the way they do, so most of the air can hit the top of the head and flow down toward the cylinder underneith.... these heads do a really good job keeping China doll engines nice and cool even tho they have to be mounted vertically and the air can't flow as originally intended so I say go ahead and mount it how you need to but check the temperatures before riding on it too hard or too long, you could always make up some type of scoop or air guide to force air over the top of the head if you got enough room... something similar to the old Suzuki gt550 how it had the air guides on top of the heads for better cooling, but most likely it will run plenty cool enough as is the way you need to mount it.
For the most part, anything will cool way better than the stock head...