You need to be more specific. Most importantly, how thick is your workstation, side to side... the smallest of the 3 dimenstions?
There are versions of the Z200 that will accept both full height and half height cards, and others that only have room to accept half height cards.
That can really change your options if the card you want comes only in full height form.
A video card can be engineered to be compatible with a PCIe x16 generation III PCIe slot ("PCIe3 x16"), but they generally are fully backwards compatible to PCIe x16 generation II or even generation I slots. From what I have seen you have one PCIe2 x16 slot, and it will be specified in your technical manual, depending on what form of the Z200 you have.
What you got?