What gear for burnout with 727

I've always started in first, then shift to 2nd, and as the tires start to grab, floor it and go into 3rd, and let it pull the motor down as I lift.
Burnouts in first do not cause instant death, or rip the spacetime continuum, or destroy the transmission. What you risk is hurting the sprag. That happens when the driver lifts with the tires spinning in first and the tires are going faster than the engine. Basically, if you floor it you're fine. You just can't let off before you go up into 2nd. If the rear brakes or driveshaft lets go or the trans breaks, the same issue can roll over and damage the sprag. After than, it loses the ability to act as the holder for the geartrain. Then the front clutch drum is enabled to spin at 200%+ of engine rpm. The factory drum explodes anywhere over 8K, which can happen at an engine rpm of only 3500.

If you can, turn the tires over in the water, then pull forward out of it and do your burnout. finish in 2nd or third. I'd say if the tires are pushing the car and sliding the front tires - your tires are ready to go.