I have a friend that had a motor of your type on his boat and he regrets the day that he sold THE MOTOR along with his boat.
Most 115 h.p. motors are 4 cyl. and have to work to put out the H.P. they are rated for. Just a suggestion but I would rebuild the motor and then buy another boat to put it on if you want to upgrade. From what I have been told, that motor is a HP giant as it has the 2 extra cylinders making power.
Just my thoughts and along with 85c will get you a cup of coffee.