Christoffer,
The ONLY place to put the diamond shaped windows is towards the top back corner as per the original. I say this for purely astetics.
The most effective place for the snap vents is almost anywhere on the side window. What I mean by this is that we have placed them in the bottom lowest corner (at least an inch clearance all round) and up where the diamond window fits. The difference is where the wind comes in and which is best for you.
The air is directed towards your face in the lower position and behind your head in the upper position.
I like the idea of fitting the two windows together as in 1075 at Le Mans in 1968 (car #9) but we are yet to do this. We are building a race car for a customer.The car will come with wide arches etc as per 1075 but will be painted as per the Yamaha car. I will be using both the diamond and snap vents in this car and more than likely fitment will be as per 1075.
Best wishes,
Robert