In order to get your boat up that high without releasing the forestay, I think you'll need a big frame lift. I think you'll need a 50 ton travel lift and a yard that is used to sailboats.

Not all 50 ton travel lifts are created equally. In Annapolis, Jabin's has a 50 ton rig that can handle our tall rig J/Boat. When we had to have the boat pulled in Cape May (which is used to large sport fisherman), the 50 ton unit couldn't get our boat very far out of the water -- let alone up to get it on to jack stands. [We pulled up high enough out of the water to allow a skiff to check-out the shaft exit; but it was only high enough to check it out.]

You might try South Wharf Marina at South Dartmouth (I don't know if they really want you to be doing your own work there -- but MAYBE they'd let you.)

There are places in Maine (like Wayfarer/Lyman Morse in Camden, etc.) -- but again, they aren't likely to let you do your own work. It can't hurt to ask.