However, if I recall correctly, the King family has made most of what he said unavailable by using the copyright law, so there may not be much.
http://www.americanrhetoric.com/speeches/mlkatimetobreaksilence.htm
where you will find such gems as:
"What do the peasants think as we ally ourselves with the landlords and as we refuse to put any action into our many words concerning land reform? What do they think as we test out our latest weapons on them, just as the Germans tested out new medicine and new tortures in the concentration camps of Europe?":