On a HKS it's worth what someone is willing to pay.  It's not all about the hours on the engine but the age also figures into the value ... rubber and plastic items age and get brittle and are more prone to cracking, seals and o-rings suffer the same.  The parts inside the carbs don't always age well ... the cost just to replace those few items can get expensive.  If I may ask, what is your engine serial number?  As for the liability,  I've sold planes complete and also parted out/disassembled with a sales agreement that indicates I was selling scrap metal and no way intended it to be used for flying purposes with pictures of the pile of parts ... haven't had an issue yet with either.  As for a complete experimental N-numbered airplane ... I remove the prop and sell as non-flying and make note in logbook or sell when out of conditional inspection ... requires an A&P to install the prop and perform a conditional inspection and make the logbook statement of airworthiness ... never had anything come back from that either.  If you sell to an airplane person most likely you won't have any problems.