You won't have any problems coming out of a 200 into a 350. The Fuel, pressurization, pneumatic, air cond, land gear(B200) ,and many other systems are identical. Bigger engines, and the electrical system from the c90b. There are a couple extra switches on the panel, but that's about it. You will love the extra power, and as posted above, it is hard to overgross the airplane.
You will probably be single pilot typed, and that means, in my opinion, that the FO can't log the time. There are lots of dissenting opinions on this board regarding that issue, do a search, or just read the regs (single pilot airplane/single pilot type. What's to argue?)
That being said, I use an FO 98% of the time because my principals like it. It can be a very busy cockpit, and will do 250 KIAS below 10000 all day long, so the guy next to you really helps, especially if you go into TEB, MDW, ATL, ect...It is also capable of some very long legs, (1500NM is easy,) so bring an FO or a good book. You know the joke: Why is a King Air cockpit so comfortable? Because you have to sit in it for so fu&*^%ng long.
I'd be happy to share anything else you want to know also...
Good luck with the interview.