Switching from foot brake 727 to power glide with brake

That converter may have to much slip at the top end as well. A higher stall 5000 esh may make a lower rpm at the end of the track with the new converter, do to less slippage, aka more efficient

My new converter raised my stall from 3000 to 4200 and my trap mph was 2 mph slower but et and 60' much better.

In other words you may need to go to the 4.56 after a converter change.

I know your itching to put the 2 speed in but remember, you just added a new "class of learning" how to leave the line, how it reacts to leaving the line............exc
as far as punching red lights leave the line at lower rpm with slow your reactions, and you can keep leaving the line the say way and making it turn green.

i don't have a 2 step or a low rpm rev limiter.
but i do have a 2 step that does nothing but turn on a light. when i'm at 1500 rpm the light turns on in my dash and i know i'm ready to launch.

These are the kind of thing that you need to adj not a converter, or a 2sp.

A new converter will give you a better 60' but is not going to help you in your red lights at all.............Launch! RPM WILL. Just saying.