Here is what NADA says.
Now with most boats you can take their values with a grain of salt, they are usually off from what's really going on in the market for boats.
With that boat, and that engine, I would think around $2000. Without pictures, and knowing how the stringers and "guts" of the boat look, it's hard to say.
But get the motor checked out by a mechanic. A little cost up front could save you a lot down the road. Force engines are not known to be very reliable, and parts can be expensive. Now if it really was well taken care of, then you may be fine. I'd still have it checked out.