I`m sure there is a thread about this somewhere on the forum, but I can`t find it. There was also a picture posted of the Panda 30 engine. It looks different from outside, and you wouldn`t be able to use the whole engine as it rotates anticlockwise. So you can`t use the cam either. Pretty much you need the head carb, push rod tubes, need to get 2 shorter studs made for the head. Apart from that you`ll have to modify the tin work on the engine, or get a German spec 126 engine. Hope this helps a little bit.
There was a Panda 30 head on eBay with everything needed which sold for £250,-, you`ll probably find some stuff cheaper in Italy.