Left Handed Drop and Complete Relief for Righty Swing

Only if your right handed swing now interferes.  It would be a second relief procedure, separate from the first one.  The initial NPR was for a left handed swing only.  The only time the player can combine such procedures is if the situation is such that the two relief procedures result in an endless loop repeating back and forth between the two.  In that case the player is allowed to modify the procedure to take relief from both instances of interference in a single move, locating the NPR which gives complete relief from both.

This is most commonly seen when a player is in an area where an obstruction and GUR (or something similar) are in close proximity with each other, but with a strip of ground between them where the player can find an NPR for each condition, but not for both at once.  In that case, after trying to drop from each condition and finding that he was always blocked by the other, the player would find the nearest point not closer to the hole where he was free from interference for both conditions.

Lets say there is a small bit of grass from GUR area, then a cart path.

Ball is in GUR, you have like 6 inches of grass then 4 feet of cart path. If you use your driver to take relief, can you drop on the cart path? Really you can take 45" of that 54". Then you'd have the NPR on the other side of the cart path?

Every such situation is different.  One's options depend on the proximity of such conditions to each other.  The player is allowed to drop in GUR or on an obstruction when taking relief from another condition, then subsequently take relief from the new lie.  I suppose if the layout was just right, that could produce a chain of relief drops resulting in moving the ball several yards from the original lie, but each case would have to be acted on as it happened.

I hope these notes might be helpful..

The location of the NPR is determined according  to  the intended swing with the club you would have used had the obstruction or AGC not been there. That could mean a lefty swing for a right-hander and vice versa, a sideways shot, a backwards shot .....

If your ball is lying through the green, your NPR cannot be in a hazard or on a putting green.  If it is in a bunker, the NPR and drop must be in a bunker.  If it is on a putting green, the NPR might be off the putting green.

You have to take complete relief from an obstruction.

You have to take complete relief for an AGC except when taking relief from casual water in a bunker.

Complete relief means for the stance and intended swing with the club you would have used.

Once the ball is dropped it is in play.

Once the ball has been correctly dropped, you can change to whatever club, swing and direction of play you wish.  If that results in interference from the previous obstruction or AGC  or from a new obstruction or AGC you can play the ball as it lies or take relief and start the process all over again.