The pair were again influential in victory at Sunderland.
Harper said: "Buying those two has been a huge statement from the club and for them both to get a goal today is absolutely fantastic. With Sone Aluko coming back as well the manager has options, which is what you need in such a tough league when you've got games on Saturday and Tuesday and we're still in the cup as well.
"Long cottoned onto how important this was from the start of the game and what a great signing he has been. He was clever as he got across Wes Brown and left him with no choice and he has brought him down. It gave us a great start to the game and we never let go.
"We've struggled away from home, but we seem to like this part of the world. We won at Newcastle, we beat Middlesbrough in the FA Cup and we've won here. Sadly that's the end of the North-east away games!"