I was active in the integration of public schools in San Francisco from 1964 to 1972. We began modestly at the elementary school level, splitting the schools into K-3 4-6 and arranging some busing movement over short distances.
Nothing in San Francisco was extreme in the integration process because the City is so compact. We made sure that the quality of the schools was raised during that first 8 year period of integration and we actually had some excellent schools (where my children, appropriately went).
Nevertheless, during the ensuing years the proportion of kids who moved to private and parochial schools increased noticeably and the number of white families that left San Francisco exceeded 60%. They were replaced by Asian, Filipino and some Latino families.
Whether the perception that schools were dangerous was based on reality, I don't know, but the perception was what mattered.
The net effect of integration efforts, I believe were negative. When I look at the Bay Area school districts that have remained overwhelmingly white, those same schools have remained quite good. The reverse is true for black integrated public school systems.
Could it have been done differently? Yes. Could I have known it at the time? No.
What would have worked was alien to the sensibilities of the prevailing educational establishment (then and now). If we had made the schools entirely meritocratic we could have made integration succeed. We needed and need now, to have most schools offering "high achieving" classes and make a genuine effort to push black kids into the high achieving classes in their own predominantly black schools. Then we need to move the black kids in the high achieving classes in the black schools into the appropriate class levels in the non-black schools.
We would achieve integration based on merit and it would be broadly accepted by students. The white schools would remain fairly safe. Importantly, in San Francisco, the Asian kids and their parents would wholeheartedly accept it; and over time, white kids might come back to the public schools.