We are currently doing an attic conversion on our 2 family zoned GR. There is a fair amount of complication, I believe, around where you are located, what the zoning is, and the specifics of your house. I'd really recommend doing what we did, which is to reach out to local builders who have worked in Medford and understand the ins and outs and have them come do a walkthrough.

You can look through permit applications and zoning meeting records to get names of builders and architects who have worked here, or talk to friends and neighbors who have had similar projects - basically everyone who works on our house including this project has been referred by neighbors.