I have been remiss in not linking to a couple of sites that propose a Winter Sunrise Alignment through the notch on Stone 58.
Novacaster Community: Winter Solstice Sunrise alignment at Stonehenge - An excellent paper from my friend Simon.
OBSERVATIONAL ARCHAEOASTRONOMY AT STONEHENGE: WINTER SOLSTICE SUN RISE AND SET LINES ACCURATE TO
0.2° IN 4000 BP
Gordon R. Freeman and Phyllis J. Freeman - A more technical paper.