I don't understand why you say the Constitution is flawed when no where in the Constitution is race even mentioned.  According to this article, "The infamous three-fifths clause, which more nonsense has been written than any other clause, does not declare that a black person is worth 60 percent of a white person. It says that for purposes of determining the number of representatives for each state in the House (and direct taxes), the government would count only three-fifths of the slaves, and not all of them, as the Southern states, who wanted to gain more seats, had insisted. The 60,000 or so free blacks in the North and the South were counted on par with whites."    https://www.heritage.org/the-constitution/commentary/what-the-constitution-really-says-about-race-and-slavery