As Josh said, there are plenty of D-owners in and around Boston.
Also, given the specific nature of your repairs, I'd suggest trying to schedule a quick "look-over" by Badger Coachworks - 259 Great Western Road/ P.O. Box 285 South Dennis, MA. 02660 USA Phone: 508.394.2680
Also, Peter at J.White's Automotive in Framingham knows soft tops very well and used to work for Badger. You could easily just stop in there and ask somebody to take a look, whereas you may find some difficulty reaching Badger. You may want to start by talking directly with the owner Jeff White, but I suspect that Peter is the go-to guy for your specific issue. J.Whites does mostly mechanical repairs on Land Rovers, not body work, but again, you're not looking for a complete restoration, only an area relating to the fasteners for the top, so I think they'd be able to help. J.WHites Auto - 1800 Worcester Road (Rte 9), Framingham, MA 01702 508.872.4752
Finally, Alan at Cityside Garage in Holliston is awesome as well, but like J.Whites doesn't do body work. He's a little further from you than J.Whites. 330 Hopping Brook Rd, Holliston, MA 01746