Automatic shifter mod

Working on a customers automatic 72 . Engine is modified L28 with close to 200 rwhp . New territory for me as far as trans . Trying to protect the engine and drivetrain from an inadvertent shift to neutral while the engine is spooled up . 
Decided to try some gate mods on the shifter . It seems to work excellent on the bench , but haven’t tested yet .

These trans will shift out of first regardless whether the shifter is still in 1st . 
Selecting second gear the trans will stay there —until you blow the engine up or shift. This trans( 83zxt) has had the valve body modified , so not sure what shift points are under WOT . Need more test and tune ! 

I have the engine protected with a rev limiter , but don’t want to shock the drivetrain by an accidental slide in neutral. 
 

Made a vid