I think you will need a 12 to 13lbs bird.I just strip out any clumps of fat from the cavities, pick the skin all over, make a paste of salt and garlic and rub inside and out. I then leave the goose in a cool place for 24 hrs.I sometimes stuff the neck cavity but never the other end, if you have a good flap of neck skin you should be able to wack in about 1.5 lbs of lean pork mince stuffing in the front.
I put it on a trivet over a tin breast side up throw the fat clumps in the bottom, do not baste. Make the gravy out of the gib minus the liver.
When you have a fair amount of goose grease in the pan drain off and pour over a mix of parboiled spuds and parsnips and roast.