You are doing most things right with the title, photo, and listing, but I would change the opening line of your actual description, which now reads:
This listing is for a BRAND NEW Lego Ninjago Golden Dragon 70503 set.
You then go on to say it has no minifigures, etc., but eBay people don't read, and you don't want to lead with a confusing sentence.
Beyond that, I don't see anything wrong with your listings. eBay would only rule in the buyer's favor if you refused to accept a return - provided your response is always "return for refund", you shouldn't have any trouble (other than having too many of these and having eBay limit your account).
Keep the descriptions super short and simple. Most of the boilerplate (you strive for 100% satisfaction, etc.) should be removed - it won't prevent bad buyers, it won't entice good ones. The shorter the description, the better chance you have they'll read it.