I saw this, and decided to comment. First of all, 28*70 years after year 3829, the year of the Churban, is the year 5789. This year is also 8*36 years after 5501, according to "the count" of the GR"A.
However, the GR"A instituted in reality a count that ends in 5786. See for instance this.
The reason may be that Din starts to count as Chesed in this year. This is profound, related to Atik Yamim, as explained. It is surely not a coincidence that it starts 420 years after 5366.
Because 420 is 60*7 is 6*70, and year 5366 is 22*70 years after the year of Din 3826. Therefore, 28 cycles (22 plus 6) of 70 years after 3826 is year 5786, the year of the Truth.
In my humble opinion, we found the background of the segment of Avodah Zara 11b, which is the background of the count of the GR"A. Thanks to Yaakov. See also this, which was also triggered by a post of Yaakov.
