Forgot to add...
Putting critical repair equipment on the ISS instead of on the Shuttles isn't a good idea. What happens if they have trouble reaching the ISS? Would you want to have to transfer to another plane before you could reach an ejection seat?
From the sounds of it, the repair kit won't be all that heavy. Just as you wouldn't want to keep the EVA suits in the ISS, you wouldn't want to put the repair kit there either.