Pietro, for what it's worth, I used a Hobby-Lobby pilot found here http://www.hobby-lobby.com/pilots.htm The item number is SIR165 Garry 1:6 Scale Pilot Head ..... $ 6.20
Not a lot of detail but a pretty good fit and a very low price. My painting skills aren't ready to paint my own. Other better pilot busts out there can be $45 or more.
I did see that AK-Models sells CMP ARFs now and the prepainted CMP pilot bust looks pretty darn good and is cheap too. BUT, they're out of stock. I've never found one of those in stock anywhere.