I made a graph of the monthly SSB distance covering nearly 2000 years centred on 1990 +-179 yr intervals - each 200 year plot span overlaps a bit with it's neighbours:
To me there are three things that stand out using the eyeball method:
1) The peaks and troughs in all spans align quite well thus showing a clear 179 yr periodicity, albeit with a gradual phase shift in the peak and trough shapes.
2) There is also an approx. 40 year periodicity among the peaks and troughs throughout each span - this may be worth further investigation.
3) the highest peak and deepest trough in a span both spend 3 or 4 spans each in one 179 yr vertically aligned period before stepping left approx 40 years (i.e. an isolated ~140 yr period) into a new vertically aligned 179 year period for 3 or 4 spans, and repeat - a longer series needs to be examined to nail this part down better.