Had the same problem a while ago with original carbs but with a "new" Holley needle and seat. If you closely compare original needles and seats to new Holley repops, you'll see the difference. The "new" is a "square post" in a round hole (body) (or vise versa - I can't remember right now - don't have them in front of me), and sticks or binds up. Find an original needle and seat (round post in round body) and replace the "new" version and you should be fine. Problem cleared up for me right away by doing this.
Best of luck to you.