I'm assuming by "school assignment plan" you mean how the school board geographically divides different suburbs and urban areas to different schools. The answer is no, because intentionally redrawing lines to divert middle and upper class students to their preferred schools (which are almost certainly the nicer schools) is completely unfair to the working class families that are forced to attend the leftover schools.

Is it ethical to pander to a specific economic class' preference to get their assets? I guess it depends on who this extra "capital" benifits.