The lease expensive option would be to cut off the bottom of the mast with a hack saw and then replace the height lost by adding a block under the mast foot. I'd recommend trex or starboard or some other type of HDPE product.
Cut out a 2" x 2" piece of trex at what ever thickness you need to equal the amount you cut off from the base of the mast and put it under the mast foot. That will keep all of your standing riging at the same height above the deck. Cut along the red line at a depth that equals the depth of your trex spacer. Then redrill the hole for the mast pin. I'd also recommend that when you drill the new mast-pin hole, you use a bushing to keep it from "wallering".