grrs, There should be a USCG capacity plate mounted on or in the boat. It should tell you the max HP. I would think that that 125HP would be close to the max BTW.
Think thats the Max on the CG plate (have the same boat in my stash of boats) but I've seen 150 Black Max on one of a friends (woof..it flys!). Another has a built 350 I/O in that screams too.