Mercury changed their horse power rating in 1982. My V-153 is rated for a 90 HP and I am putting a 140 HP old rated, 115 HP new rated engine on it. The transom on the V-153 seems to be holding up. Secure the motor by putting in four bolts through the transom tightly, clamp screws tightly, and big washers or plates to distribute the weight of the bolts on the end of the nuts. Accerate gently, no sudden turns, no sharp turns, and watch the waves ahead.
Deep V's can handle waves better than tri-hulls, and some hull brands were not engineered correctly and were subject to cracks, flexing, and breaking.
There is a design flaw on the V-153's that cause the hull to roll over if turning sharply at low speeds. Really scary the first time it happened with a 80 HP Mercury on it, and would be really really scary with a 115 HP Mercury. I mentally am aware of the problem and avoid that set of conditions.