Well everyone keeps saying "it wasn't in writing", "need to be in writing", etc but everyone is making it sound like you're powerless in this. The way I see it, you can benefit from this BS too. Who's to say the engine or pump was in the boat in the first place? Perhaps, the verbal agreement (that wasn't in writing) just as easily could've been to replace the steering cable, drain the fuel tank, and clean the lines. The engine was siezed and maybe he just wanted it gone so he could install a new one himself....or maybe since he couldn't afford to pay for the work done, he agreed to give you the engine as a trade for the work you did. The title only covers the hull... The components aren't required.
As a more honest option... A mechanics lien may be involved but what's filling out a few forms after all you've been through all this? We're all guilty of being lazy at times but for $2000+, I think it'd be worth the effort.