My favorite answer to most UX questions is: "It depends".
How will the redesign be done? Full redesign with a rewrite of navigation and content? Or keep the existing content as is, and just redesign navigation?
My next question is: What are you trying to organize? 600+ words sounds like a lot of words to organization, and I don't believe that you really need to card-sort all of these words?
Well, here comes my tips:
1) Focus on user tasks rather that information about the organization.
What are the most important tasks for the visitors? Is it to read about the "Postgraduate" or is it to "Find relevant studies" or is it to "Find staff"?
User tasks should be the primary motivation in your IA work.
2) Start with navigation.
The user needs to know how to find stuff, and he needs to know where he is.
3) Do some measurement.
IA can be measured. "Task success" is definitely the best metric to use when you evaluate the navigation. You can also measure the "lostness" by counting the number of steps the user used to find a page, and compare this to the minimum number of steps that is actually needed to find that page.
3) Use other methods.
If you really need to test several hundred words, you should turn the card sort method upside down. Instead of presenting all words at once and then let the user organize them into groups, you could give the user some groups and let them fill the groups with their own key words. (This method probably have a name, but I can't remember at the moment :)
4) Use a tool.
There are several online card sort tools that will help you. Just google "card sort tools" and take a look at some of them.
To ensure a good IA over time, training is important. A couple of days with the web editors (or maybe all contributors) will ensure a more uniform IA to the site.
Creating a wire-frame isn't that hard. Take a look at www.wirify.com, which I used to create this in seconds: