I like your proposal, but there is one mis- calculation; it was 120 years, not days. But also; the flood happened 40 days and nights, so if Aug 17 is a possible date for destruction and 40 later, it's just as that Moore fellow suggests here:

posted by Dru:

dru815-1.htm

calculation results

From date:Friday, August 17, 2012

Added 40 days

Resulting date: Wednesday, September 26, 2012

It's still the 29th of AV, on august 17th!

kari