I use Crash Value to calculate the Dow and SPX expected bottoms.
Crash Value lines up with the H&S target of 3800 on the Dow. It is a bit more optimistic on the SPX, having around 490 as Crash Value while the H&S target is about 300 on that index.
Crash Value is calculated from the 1982 base lows with a 7.5% annual rate of return, which is fair considering the dividend cuts we've seen in the past decade.