While my soldering skills of the drain adapter were spot on, apparently my measuring skills were not. After fitting the drain, a small piece of PVC, and the threaded adapter to the top of the pipe, the shower drain was way to high. So I had to unsolder the brass adapter, cut off the copper trap, and replace it with a PVC one. The upside of this is that I get a nice fresh clean trap to work with, the downside is that there are now many more potential spots for leaks.