I am considering altering the keel on a 34' Sabre from a 6' draft to a bulb/wing shoal draft keel. Are there any problems or considerations that I need to know about prior to making the modification? I haven't bought the boat yet, but the 6' draft presents a real problem for the waters that I sail in. Any recommendations on a good boatyard to do the work? The boat is in Marblehead, MA. Thanks.