I use some pretty lean cuts of beef without a moisture problem. As you can see from the recipe, I also trim off any external fat. The dry cure should help it maintain moisture while smoking, maybe basting with peanut, or some other flavorless oil, once the bark has set might help as well. Also, you might forgo steaming the whole chunk and instead just briefly steam slices if you're making sandwiches.
This won't be like Katz's New York deli style. The texture is more like Canadian Bacon if that helps you decide what to do.