Just food for thought,
one [of several] reasons a Powerglide works so well in drag racing is because it causes the properly selected converter to work at multiplying torque. In low when leaving the line because of the low gear ratio the Powerglide "stays on the converter" longer during low gear, thus, multiplying torque longer.
At the shift, again, it is back on the converter multiplying torque until the driveshaft speed becomes closer to engine speed. This is the basic reason matching torque converter selection to your combination is very important
Other Powerglide advantages are lighter weight and less rotating loss.