We've got to deal with this old pipe, which we think is too tall to use. Will probably have to cut it down before installing the new wax ring and toilet.

Now a day or so later... I didn't have a camera with me to capture this step, but we got a brass "closet flange" to mount the toilet to the floor. This fairly important item was deemed unnecessary by the previous builder. Once getting the new flange on, we were able to shape the old lead pipe to fit the new flange perfectly without any cutting. Then we put down the wax ring and a few other bits and we were flushing with success!