Spy,
Gear drive set ups are for gear driven cams. Chain drive set ups are for chain driven cams. If you are thinking of doing other work, you may postpone this. If you are doing research or have a progressive build that will entail the use of several different cam setups through out the process of ultimizing and optimizing the performance, I would do it now. My answer is not meant to sound obscure. I like gear set ups for cams as a personal preference. I do not have a clue as to what you are looking to accomplish and can not advise you without knowing that.
Mike