Single maps of Dorchester from the early years provide a general view of the buildings and property owners. The introduction of the fire insurance atlases in the third quarter of the nineteen century provided exact boundary lines between owners.

You can find historical maps of Dorchester online in a number of locations, including the Leventhal Map Center at the Boston Public Library, the Masscachusetts State House Library nd at Digital Commonwealth.  The Dorchester Historical Society can supply digital copies if you contact them.

The Bromley atlases from 1894 through 1933 are consistent in putting the same neighborhood on the same plate.    The 1898 atlas has an index plate that will allow you to see which plate number you want for the area you want to look at.  The 1874 Hopkins and 1889 Bromley atlas do not follow the same pattern, but those atlases do have their own index plates.  For other atlases, you may need to try several plates before finding the one you want.