Yes likely you can chisel off the top 1/2 inch or so and then replace the drip edge. Several shops will make you drip edge with an extended flange! You sound like you are on the right track! Let me know. You may need to use roof tar to get the shingles to stay down but only use dabs about the size of a silver dollar! please let me know how you did i can even show you pictures of my fix job!