Is there any other meat I can sub for the duck? I can't get readily get that here. This recipe sounds so good I am hoping I can re-re imagine it!...

Nancy, you can use chicken (dark meat) and turkey too. If you are using turkey, I suggest subbing about third of the meat with finely chopped bacon to make it more moist. I do it all the time and they are wonderful.

Agree with Lisanne about recommending a poultry substitute for duck in that meatball recipe.
But/and. There are many lamb-orange recipes already made and evaluated by other cooks...maybe try one of them if you like that flavor combination
*Lamb and orange tagine
https://www.google.ca/search?q=lamb+and+orange+tagine&oq=lam&aqs=chrome.0.69i59j69i65j69i57j0l3.1534j0j7&sourceid=chrome&ie=UTF-8
Lamb stew with orange and fennel (this one by Diana Henry, who was featured two or three times this April answering questions here)
https://www.saga.co.uk/magazine/food/recipes/meat/lamb/lamb-stew-with-fennel-orange-and-rosemary
Lamb Khoresh Stew with Orange (by Chocolate and Zucchini, a very good Paris blogger)
http://chocolateandzucchini.com/recipes/meat-charcuterie/lamb-and-orange-khoresh-stew-recipe/

That recipe does sound delicious. I would go with another poultry, especially ground chicken for example. Chicken with orange sauce is delicious too.