The King Air 350 is only a development of the 300 and on the same TCDS, like a 250 wich is just a disguised 200.
It is correct the EASA Rating for the 350 will read 300/1900 and include the 350.
Last year i got a very good Offer for a King Air 300/1900 EASA Typerating from Aerotours in Straussberg Germany. The credit you some hours, if you have a valid 90/200 Rating.
As everybody else in Europe the use the Finnair KA300 Sim in Pori Finnland.