As long as it can dissipate up to around 10kW of heat and has enough flow your chiller should be fine. Usually just run them open, i.e. hot water down the drain, if there's no chiller available. One nice thing about that is that it doesn't rely on power to pump or cool water. Be wary of water leaks, if these are anything like the 165/7/8 with the 265 exciter then the exciter is also water cooled and could spring leaks inside (as could the head) - as you'll be aware, water and electricity don't go all that great together.
Do you know the exact model? The 2000 series came in a few sizes IIRC. Can figure out the expected power on a good tube from that. Doesn't mean yours will make that, don't know how old the tube is, what the gas pressure is like, if the mirrors are still aligned well and all the optics are clean.
Sitting for 6 months shouldn't be a problem.
Keep us posted on your progress. Don't continue if you get stuck somewhere or are unsure... ask for help, there's people here that know these systems well. Even more so on Photonlexicon.
I don't know these well enough to offer any other advice...