Most folks are advocating a preliminary day cruise to understand the systems of the boat before making the 100+ mile trip. Most people are also advocating getting a partner or hiring a captain to do the trip with the OP.
I agree, the OP should certainly spend a few days sailing his new boat before heading off on the journey. Push the systems, and the captain. Drop and hoist anchor, practice reefing, heaving-to, and push the engine. Better to break something near a friendly port than during the journey.
For basic equipment I would make sure the compass is sound, the depth sounder and VHF works, and you have a handheld GPS/chartplotter. Get the paper charts and the appropriate guide (Ports book). Make sure you carry a radar reflector (I assume this boat won't have radar). Fog is always a possibility on the Great Lakes.
Having additional crew is always a good idea, even for a day sail, but if that is not possible, then this is certainly a journey doable by a solo sailor. Hiring a captain seems unnecessary to me, but that's certainly an option. The key for me would be to go slow. Plan some reasonable hops, but have no schedule. Be wise to the weather, and keep an eye out for other traffic, especially freighters. They move very fast.
A Pearson 28 has a reputation of being a good, solid boat. Assuming this one is in decent shape, it should have no trouble handling this journey (I'm assuming the journey is planned for June-August). The OP is a novice, but not without experience having raced on other boats, and done the Port Huron Mackinaw race. It's certainly a doable trip.
Enjoy the journey. I've never sailed this stretch, but am well acquainted with Georgian Bay, the North Channel and Lake Superior. The Great Lakes offer some of the best cruising anywhere. Enjoy it.