iboats.com has a good forum and sells a lot of parts. Some VERY experienced boaters on there. I'm happy you bought one in good shape, as boat projects will sink you financially more often than not.

In general i/o boats need a little more special attention than outboards. You have a big hole in the transom where the drive goes through, so take a look closely for leaks when it's in the water. Often on older boats you see the transom rotting out when water penetrates and soaks the wood. When you torque down on the bolts you can see the transom squeeze like if you sat on a sandwich. The exhaust hose has a tendency to want to leak with age too, which can also let water in.

Change the oil in the lower drive unit. Check for oil. Those seals are prone to leaking with age and they let water in. Also pull it and change the water pump in the lower drive unit. They should be changed every couple years.