Just realized, Foster, that that sauce recipe will not likely be enough for 15 people. I'd probably start by doubling the stock and bourbon (definitely look for lo-sodium, though, since reduced stock can get salty quick. (Purists would say make your own stock, but that's way too much work for me.) If you can find "For the gourmet"-brand stocks, those are outstanding, but I don't know if you can get them other than by mail order; I'd probably just go for whichever one in your store that has the least salt.
You probably should be warned: I'm like zombieslayer, I rarely do recipes. So insofar as any of the above resemble recipes, the ingredients should be considered approximations. Fudge and "that looks like about a cup" hopefully will get a good result for you. And it is impossible to get too much cheese in mac-n-cheese in my opinion.*
(*Way back when I first found a recipe for fettucine alfredo, it called for 1/2-3/4 cup of parmesan/romano cheese. When I make it now, I use a minimum of 1 1/4 cups.)
Last warning: if you find the lamb, use a hot grill and don't overcook it. Better to have it rare in middle and char on outside, IMO, than risk medium well or worse. Those little things cook damn quick, and if you take them off rare, they'll be close to medium by the time they've made it to people's plates.
And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove what is that good and acceptable and perfect will of God.
Romans 12:2 (NKJV)