That's the stuff... And I'm not sure about the BBQ idea, does it have a hood? And does it hold a temp well? I'd just use the oven.. I cured my engine cases in it, then cooked a heap of garlic and onion after to hide the smell from the misses haha
As for masking, I'd just use tape man.. If not then find some steel tube the same diameter and cut it about 1 1/2 inch long and put it in the holes