If you understand how the 727 works you'll see besides controlling the shifts there isn't any magic in the valve body. Assuming a non low band apply valve body is being used. There is no way to shift 1/2 any cleaner. First gear applies the rear clutch when the shifter is moved into low. The low roller clutch (sprag) holds the rear drum. You are in first gear before the car ever moves. In second the forward band stops the forward drum. When this happens the low roller clutch over runs. Nothing has to be switched off. So in essence the trans is either in 1st or 2nd. There isn't any time when the output shaft isn't being driven. Timing of the forward band release and application of the forward clutch is the key to a good 2/3 shift. Plenty of ways to do it. The bottom line is to get the timing so both units aren't fully applied at the same time. A very firm 2/3 shift is more than likely applying second and third at the same time. Use only as much line pressure as needed to keep the clutches and band from slipping. My car doesn't need much. Right around 125psi. When it's right the clutches and band will go a long time. My car has never hurt a band in over 750 passes. Forward clutch was still useable at 500 passes but showed a slight amount of heat. Rear clutches were like new. The only real issue I have with the turbo Action is the amount of time between shifter movement and the actual 1/2 shift. The shifter needs to be moved well under the actual shift point on the 1/2. The 2/3 is much closer in time in that respect. As far as leaving the line the valve body plays no parts as long as it has sufficient line pressure set.
Doug