how many people still alive in the kkk actually participate in a lynching?
Actually a pretty good question. In the 50's, 60's, and early 70's white resistance in the South was led by White Citizen's Councils where "respectable" segregationists in public office and the business community tried to slow or reverse desegregation. The local muscle to rough up Freedom Riders and shoot into occupied houses and burn churches was delegated to the Klan. In a typical Southern county the White Citizens Council normally included the Sheriff, Chief of Police, Mayor, President of the Bank, County Superintendent of Schools and so forth. The Chief Deputy was often the Klan head, supported by all the good ol' boys he went to school with.
The Tuskegee Institute has recorded 3,446 blacks and 1,297 whites were lynched between 1882 and 1968. The last full public lynching in the South was probably Emmett Till in Mississippi in 1955. After that, people were killed (Goodman, Chaney, and Schwerner in 1964 for example) in racially motivated slayings, but these more nearly resembled assassinations or mob hits rather than traditional lynchings. In the decade from 2000 to 2009 a number of high profile cases which had ended in hung juries were retried and convictions obtained.
So to answer, there are probably two or three dozen inmates in prison today serving long sentences for racially motivated murder, attempted murder, arson, and similar violent
crimes. I believe six of them are there for trying to kill Morris Dees. To the best of my knowledge, all of them were members of the KKK or a successor white supremacy organization such as Aryan Nation, or had close ties to such organizations. The traditional meeting place is the Stormfront.org website.