That's not the stall. Put it in 3rd gear, get rolling at about 10 mph, mash the throttle wide open quickly and see what the tach jumps to. Do not hold it wide open, just a quick stab to see where the RPM flashes to. That will be your flash stall.

CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax