Good Stang/Trans shops in MA

You can try this place, www.mperacing.com there in Whitman, I think thats pretty close to you. They can do the swap for you, it's not cheap though. I think they charge somewhere around $2000 give or take for the whole thing depending on what parts you use ( used t-5 or new, and so on). They seem like a pretty good shop, I've dealt with them a few times. Give them a call I'm sure they can help you out.
 
If you are willing to travel a little, SRA transmissions just outside Newport, RI did a T-5 R&R for my old 84 and did it for a good price. Buddy Souza, the owner, is a friend of mine and I can assure you his work is top notch. He specializes in bulletproof autos, but knows plenty about manual trannys as well. If you want I can get his # for you.

Eric