Building a strong street/strip 727

What 'failed' on the last unit?

2nd gear band is trash. it will go into 2nd gear if im coasting and shift it but if im on the throttle and hit the 1-2 shift it wont shift into 2nd. I will be going with a reverse pattern manual valve body and upgrade pretty much every moving part in the trans.

next question?

is a 4 gear planetary mandatory for 600hp street strip?