Thanks for all the input. decided to use a combination of the methods and ideas given. Cut off the shackle at the old eye splice then sewed the 2 butt ends together with very thin steel line and covered with elect. tape. Then pulled it thru the sheeve at the top of the mast and out the bottom...worked like a charm. We had an eye splice and shackle put in the new one first.
thanks all for the input..
cheers
Colin