Who makes a 125 hp outboard motor? How much does it weight? Has the boat every been in a freeze thaw cycle environment?
Usually the 115 hp is plenty of motor. Once you get over 30 mph the boats begin to be a little squirrelly. The larger motors are usually used when the boats are heavily loaded--such as Jay's will be for a long Alaska trip.
I would be concerned about the transom in a 1988 boat. I have seen a broken transom with a larger motor, even in a newer boat. The boats at the time were rated for a 70 to 75 hp 2 stroke. Although there has been no substantial design change, be sure that there is no moisture in the transom. I would use a moisture meter, sound out the transom, especially when the 90 hp is off the boat--and you can check the mounting holes for potential water intrusion.
