A tricky addition to a potentially historic building.  A mid-century modern townhome abutted on both sides and a part of a potentially historic group of homes that in the beginning were of a very singular and simple ethic and execution.  At best you don't compete and you don't copy.  The worldwide accepted ethics of historic preservation, addition and adaptive-use say do those things you need and want but maintain the integrity of the form, scale, fenestration (openings) and materials of the original. There should be contrast between old and new--so that there might be no questions as to which is which.