I've got one of the older blue and yellow pc 200's. Good old machine but it doesn't have auxiliary hydraulics on the boom. I notice a blocked off set of valves in the the valve body. Can aux. hydraulics be added for attachments on the boom.
Those machine came with the auxiliary valve as part of the valve block. It was usually used when people added a thumb. Yes you can use it. The circuit relief cartridges usually were not installed though so you would need those or an auxiliary relief valve.