Re: Hull Rating
I do not believe there is a fine but you become 100% liable. In the event of any accident you can be found at fault and an automatic guilty. These are mostly here-say and rumors.
The iboats policy is ..... We do not endorse nor reccomend any unsafe action such as exceeding the HP rating of the hull.
With all the mandatory said...... your boat is a 1985 and I would be darn sure that the transom, stringers and flotaion are in good shape before I repowered regardless of the HP.
The other thing I would advise is to contact the USCG. Here in VT the USCG has been on a streak of inspections and the most common fault they have found has been outdated flares.