I have never sold an engine on RJ- However when I sell any engine or transmission, in vehicle or not, I provide a photocopy of all receipts showing machine work or parts.
I keep originals to calculate my cost basis and profit margin, but providing the receipts offers a fair measure of protection as well as credibility on what I am selling. I would never represent any item based on what a prior owner had told me without personal verification.
If you have any support for what your are selling it might differentiate your add to get it sold.
Also shipping is always an issue-offer a link to
www.uship.com, a buyer can post a shipment of an item like your motor that he is thinking of buying and then get transport bids. I moved a 32 ford pickup body/cab/bed/fenders from Green Bay to MD for $325.
Maybe this will help you get it sold
Scorp