I had a '62 single carb. As I remember the filter, it was rectangular and fit in front of the battery box and oil tank. It fit so close that serviciing the filter element was a guaranteed way to scratch the paint on both bat box and oil tank.
The filter element was so open that it removed only small leaves and insects. (I'm being just a little facetious)
My present dual carb Atlas used a similar air box, which I have in a bin somewhere. I will try to post a picture later today.
Slick