727 having a few issues

Wow, your thread got lost in a hurry.
As to the shudder;
When this happens, is the selector in Drive or in manual Low?
You know that brakes themselves will do this,right. Park the car on a decline and put the tranny in neutral, then slip the brakes to let the car roll downhill in a forward direction.See if you can duplicate the shudder.Front drums will do this more often than front discs.

As to the slip in that corner,
are you saying that the rpm went up, while the tranny stayed in whatever gear it was in, and it was not initiating a gearchange?

As to the late shifting
Do you know if the tranny and the rear gear-ratio are a matched set? In other words is the governor stock and the rear ratio the same now as it was when the car was first built? What I'm suggesting is that the governor for say 2.76 gears is, or may not be, the same as the governor for 3.91s. A transplanted high number rear gear will fool the tranny into shifting early. But a transplanted low-number rear gear can cause the opposite, a late upshift.
Also, in a stock VB, the governor pressure is resisted by the line pressure plus the throttle valve pressure. If one or both of these latter two is messed up, then the governor can rule, or it can be over-ruled. It's a delicate balancing act, with even the tire diameters getting into the act.

Does your carb have the proper MOPAR specific throttle arm, with the correctly located KD pin?This is very important for proper TV pressure synchronization.If you don't know, send a pic.