Your Spectrum is not a particularly well built boat in the first place. Wouldn't exactly be my first choice for overpowering. Please stick within the max rating of the hull.
I have a 1990 24' Spectrum (I don't have a model number, but is is kind of like a pontoon boat except the hull is all more or less one piece split out like 2 pontoons). It is rated at 90 HP MAX. Hope this helps.