Agree with above. We've had several people come on here, and I think we probably discourage them from this. Ride a café for an hour or two, and you'll probably figure out quickly a week long trip imprisoned on a torture device, is not the way to go. If the KZ550 has been kept up, it would be fine for a long trip. I don't know how big you are... I'm 5"10" /210lbs. That bike would be marginal for me, but back in the day when I was your age and about 170, I wouldn't have thought twice.
The KZ550 is a very capable bike. Like said, I would go through the brakes, change all fluids and make sure tires are up to snuff. Also make sure the valves are within spec, timing chain is adjusted and keep a very close eye on oil consumption, and clean the carbs before the trip and add fuel filters. I would talk to hikers and gather the best light weight stuff I can find and as A.D. pointed out you can't have enough clean socks. Rain suits can be bought cheap and packed small. Back packs are not an option. In your tool bag, add zip ties, duct tape and electrical connectors, along with a good leatherman tool and wrenches and extra fuses. When I tour on a older bike, I always swap the fuse box for a newer blade type. easy to replace and seem to be more dependable than glass fuses.
I'm not sure if you have a line on a KZ550 for cheap or one in the garage, but when touring, there is little replacement for C.C.'s. A big loafing engine is nice to have for droning on the freeway. If the majority of roads are going to be "B" roads then something more lively is more fun. If this trip is going to be all interstate, then buy the biggest bike you can afford, for slower "B" roads the KZ550 is fine and it's plenty capable of rolling on interstates, the engine will just be a little busier.
I think most here have been on a long trip on a small bike, and most at some point in that trip probably would have enjoyed a bigger bike, but we've also been on that road that a midsize bike was probably more fun. I ride to Cambria a couple times a year on "B" roads, and my Aprilia rocks! But when I visit my home in New Mexico, I use an FLH, it's just more comfortable for 12 hour trips from Socal to N.M.
I think you mentioned college, you're young, a long trip on a KZ550 will be an adventure you won't soon forget. Get out there and have some fun.....