Leg of Lamb

Going to do it on the green egg Sunday and never done one. Here is my plan:

Debone the leg of lamb and season with Rosemary, thyme, salt and pepper and rub a lemon cut in half over it. I plan to let it sit in the fridge until after church on Sunday a.m., i will probably put it in a roasting rack in a pan so i can catch the drippings.
I have never cooked one, but this roas tis about 5 lbs after deboned, i think 30 minutes a pound at 325 until the internal reaches 150. I want it medium rare and not over cooked, so kind of guessing on the 150 internal.
Anyone ever done one of these, diff. recipes or rubs, suggestions, comments??