Just a guess based on what little I know, but looks like a Mark 40 or KF9 or KG9 type motor. Obviously racing tower, foot, prop, and pipes. Has the forged transom brackets so somebody new what they were doing when they put it together.
I saw that ad, and FWIW, for what he's asking for the boat motor and trailer, I doubt it will take long to sell.
Hope this helps.