Buongiorno Maurizio, you are away a long time.
The early Honda Sandcast originalally came with the 2 hole airbox. There were 2 variations with the reproduction from Yamiya being the early 2 hole. Around mid production of the Sandcast bikes, this was changed to a three hole variation in order to overcome cracking of the early 2 hole design. All diecast bikes came fitted with the 3 hole type air cleaner box
If you want a 3 hole airbox then the easiest fix would be to drill a third hole in the Yamiya reproduction. I am not sure if the 3 hole bracket aligns with the existing 2 holes but you can try before any modification. A presto