Ferrari California - radio unit and speakers upgrade

Hello guys

I've got a Ferrari California with stock radio and would like to upgrade audio system but there is two ways connected with radio unit:

First way : buy a chinese headunit designed specially for California - i've got a sad and painful experience with this kind of multimedia unit in the other car (Maserati GranTurismo '11) so i'm not sure this solution.
Second: buy a Kenwood, Pioneer or any other company universal 2DIN Unit. But what would I do with space on the left and right side of screen? Is there any fitting cover to buy or will i have to make it custom? What with steering wheel control - should i buy Maserati Can to Can converter? It will work?

And second question about speakers - would replace it, i found this thread :
https://www.ferrarichat.com/forum/threads/upgrading-the-ferrari-california-t-sound-system-with-aftermarket-components.600891/
Could somebody tell me that the speakers diameter is fitting? I didn't remove cover yet and i'm not sure about that.

Thank u guys!