4.2 kickdown lever

Increased line pressure does that too. Again it depends on the valve body and what you are trying to accomplish. 170 psi pressure or higher which is what most transbrake operate at, speeds up everything. The trend with these kinds of pressure is to decrease
The lever ratio because of overlap.
Sorta. As long as you use a wide band, the 5.0 lever is a big plus. Otherwise, it really doesn't do much. No 904 ever came with the 5.0. That was a Hemi only option and they used a wider band than all the rest of the 727s. That's why you need the widest 904 band you can fit in if you use the 5.0 lever. I believe the widest that will fit is 2" wide in the 904.