I'm going to be honest and throw this out there because I would want the feedback if I were selling.
Based on the info you provided, you are asking about double what is fair value for the engine. Without leakdown or compression numbers it's going to be a harder sale. Also, if the engine was recently gone through, it would be beneficial to state what all has been done during this service (what was changed, checked, etc.). How many miles are on the engine? How was it used? How long since last overhaul? Who is responsible for removing the engine? Will you ship?
For reference, $5500 is about what McMark is rebuilding 2056cc engines for and you get a "0 mile" engine knowing all of the specs and details along with it. Check this recent posting for an idea on pricing:
http://www.914world.com/bbs2/index.php?sho...=328089&hl=