My question is does the south node correlate to something specifically from the past incarnation?
Yes. Pluto, by house and sign, correlates to the Soul's desire nature
. The South Node correlates to our past life habitual emotional patterns, created relative to the Soul's desire nature, brought into the present life. These reflect our past choices
. Because of habit, fear, resistance, etc. we tend to repeat and repeat the same old choices.
The evolutionary intent is to change, to deepen, the Soul's desire nature. After repeated disappointments, disillusions, trauma, etc eventually a Soul/Ego starts accepting that what it thought it knew no longer works, is no longer enough, and starts embracing the need to change, that is, the need to make different choices. Typically they don't know how
to make any other choices. Most of us equate what I know with who I am. Thus a larger sense of who I am is being called for.
That is why the North Node is as far (180 degrees) away from the South Node (the past, the known) as it can possibly be. In other words, evolving requires making choices that embrace stepping into an unknown, the exact opposite of what is known. What is known is what causes us to feel safe, secure, etc. even if what is known is dysfunctional. In stepping into an unknown, unconscious fears and insecurities arise, relative to past forgotten memories, which explains why moving into the unknown is so difficult at times for most of us.
In terms of the next life Sun being the sign of the present life North Node, I believe it was stated that is often the case, but not always.
Why Sun as past life North Node sign? The North Node is future of our Moon, our personality, our sense of self. The Sun symbolizes actualization. This life's North Node, the evolutionary potentials
, the direction to move in to break the hold of the past, would find expression in the next life as Sun, the intent being to directly actualize
(Sun) those potentials, as life purpose (Sun). Thus the intention to turn potential into reality.