Switching throttle position was certainly done for someones personal preference, perhaps available at dealers and shops as accessory.

Left hand throttle is not difficult to learn. A good way is to use both grips both for accelerate and decelerate, until speed control with your left hand becomes natural and you can leave the mag grip alone. Then you got the Indian way of riding!

If you simply can switch over the cables depends on a couple of things. How your carb and magneto is set up, and if one of the control spirals is changed or not. Original when you turn the grips, the left control for the carb is pulling the wire, and the right control for the magneto is pushing the wire. The spirals in the grips are both machined as right hand coil direction.

The magneto can be set up with the lever pointing in either direction so proper function can be had push or pull, and carb lever could be modified for push roll on, but that's really NOT a safe way to have it.

Most likely your right control spiral is changed for one with left hand coil direction, so you have pull function for the carb. However in any case it is really a very good idea to change the whole package in one go for new parts. Spirals, sliders, wires and sheaths (covers) readily available from many providers because all those are subject to wear and that makes the controls sloppy, jerky and heavy. You won't belive how silky smooth, precise and easy new well fitted contols are and how that makes riding so much more relaxing and joyful!

Be really really careful fitting the new wire sheeths as a miniscule kink or bend makes them very heavy in usage and very difficult, but not impossible, to fix a damage on. They are much more sensitive for kinks than modern bowden wires are, and fitting of the length and position at steering lock needs to be set exactly right. Absolutely not too short so the wire stretch around the headstock or too long so it gets in a jam or get crushed. With even the smallest kink or bend, both the sheath and inner wire needs to be straightened.

If you can get to the point where the wires hardly snakes at all when you turn the controls, you have come a fair bit on the way to perfect.

My right side twist grip only turns 1/4 and my left has a 1/2 turn in it. Much more than the magneto requires.

If the mag doesn't need full travel of the grip it is ok I guess. But if I understand right, you need to investigate the grip internals. Original the grips has 1/2 turn travel.

Maybe it is as easy as the tiny wire sheath clamp on the handlebar outside has shifted. If the wire is kinked and hard to pull, the sheath has a tendency to be drawn in the handlebar.

A good idea also is to check on the 3 tiny rivets that holds the controlspiral in place at the back of the handlebar grip, they have a tendency to loosen up and disappear. The spiral should be firmly attached to the grip tube.