I always say, the quality of your squad should dictate the formation - and not the other way around.
I would start by thinking of our biggest weakness - our defensive mids. Our greatest strengths? Wingers - Chiesa and Cuadrado. Our highest quality forward is Dybala - what is his best position? Second striker. From there the team picks itself.
----------------------------SZCZESNY----------------------------
DANILO-----BONUCCI-----CHIELLINI-----SANDRO
-----------------ARTHUR-------LOCATELLI------------------
CUADRADO-------------------------------------------CHIESA
-------------------DYBALA------------------------------------------
--------------------------------------MORATA----------------------
Couple of additional comments. The above formation easily transforms to 343 with Sandro and Cuadrado becoming wingbacks. Locatelli is a "lock" in that formation - his partner, however, is hard to pick but should ultimately go to the player with the best form. I think Arthur is the other midfielder who at least has great qualities in possession. Kulusevski would be best as a Dybala 2nd stringer while Kean and Kaio would be Morata replacements. Should one of Cuadrado or Chiesa not be available then Kulusevski should again be looked at while Berna should kind of be avoided given his lack of quality. I see Kean as a player who can play out wide but not in a 442 so much so we have a lack of back up options for Chiesa.
Also note I went for Bonucci and Chiellini rather than De Ligt. If both are fit, I would go with that pairing for now for as much as possible given their excellent understanding with eachother. This squad is VERY young. Having experience out there is quite valuable right now - especially in defence. Eventually De Ligt will and should become first choice.
Right now we need results and we need to stop leaking goals. We need a solid system. I think this one is the one we should go with for a while.