This may be dumb to those of you who dyno and extract info from graphs like this often but I was playing with some numbers and this is what I came up with.

170whp@~5400RPM
199wtq@~2650RPM

Optimum tq= 2650-4400
Optimum hp= 4300-5500

Median for optimum tq= 3525
Median for optimum hp= 4900

Sweet spot= 4212.5

Estimating a 2000 RPM fall at shifts means optimum shift at 5212.5

If this is wrong please correct me and I understand its more in depth and their are more variables but this seems like a fast logical approach to finding an ideal approximate shift point.