The "B" in CB stands for "basic", as in no capability to put in a third seat--which is why the PIC sits on the left in the C model.
...just to clarify: ones you get a 2 seater you got two seats - no way to change it (easily), but you can still order a 300 CBi with optional 3-seats and left-hand PIC.
PS: how you doin' Gordy? I saw you left HAI shortly after I was done there (you tought me the "real-world-flying part" of my CFI at the time... helped me a lot at during the last two years! Thanks again!).