I don't think those two specific buildings being located elsewhere would probably change the story that much. I think what's more important to consider about the setting is the small town, semi-rural area of Maycomb, described by Scout early in the novel as "a tired old town" and its residents, many of whom still live the traditions and cultural norms that have been in place since the Civil War--or even before. So much of what makes Harper Lee's novel so compelling is this small town setting in the Deep South in the 1930's, a place where institutional slavery had ended decades before, but where blacks still lacked any significant gains in equal rights in the years prior to the publication of Lee's book in 1960. When the deeply entrenched prejudice of the Deep South was coupled with the small town, intolerant mentality of many of Maycomb's residents, Lee effectively underscored the hopelessness of Tom Robinson's situation as a black man accused by a white. The same story set in a city in the North would create a situation where Tom Robinson might have had a chance for an acquittal--eliminating one of the book's major themes, which was that Atticus provided the best defense for Tom Robinson that he knew how to provide, despite the fact that he knew he was beaten before the trial even started.