How much RPM drop from park to drive with stock type 340 convertor

I believe the "Hold the brake, florr the gas watch the tach" is called a "stall speed " test. it is used by tranny guys to check the converter.

here is a description from the web:

Put the pedal to the metal While pressing on the brake pedal, press the accelerator to the floor for two to three seconds. Don't exceed five seconds, or you risk blowing out the transmission. The RPM the engine maxes out at is the stall speed.