I was wondering could I use this recipe for just beet beef instead of pork

Can't say I have ever tried it with beef, but worth giving a shot. Typically where I grew up, almost all BBQ was pork and chicken. I have used my mustard base sauce on Beef Ribs and Brisket. If you try, I would use a cut like beef chuck roast that has lots of fat and collagen. Similar to a pork shoulder or butt.