Hi Blake.
The torsion keys are not an option on these trucks really. If you don't offroad and are just in it for the look, a few have done it with mixed results. Not in crew cabs though. The majority running them seem to be the RPO ZR2 models. The higher wider suspension may play a part there?
Why not?
Well there are a couple things I can think of. The suspension only has room to adjust for the Z height to be cranked to a point. Beyond that there is no way to correct the caster and camber. This point can be achieved with the stock torsion bar adjusters and keys. Why would you buy keys and have to back them off when the stock keys will already reach that point.
Second is the limits of the ball joints. At maximum Z height you are very close to binding the ball joints. The Stock bump stops are pretty soft and will not completely protect you from over extending their range.
The upper ball joints are the worst as the upper a-arms are short and therefore travel further. This can be remedied by changing the upper a-arms. That will correct the angle and give you some more room, but you still have the issues with the lower a-arm.
Now the next issue. The CV joints. Adjusted for max z height we already have problems tossing CV boots. Most can be remedied with a better clamp, but still it is an issue. if you intend to go further you will likely need different boots that are softer and will flex harder. That could mean they are weaker and may be damaged easier? I don't know.
That will put the CV joints at a very steep angle. I don't know what the range of operation is for the joint itself as the boots seem to be a limiting factor here.
We did have one member run the torsion keys for a while. His was due to the weight of a large winch attached to the front. He was unable to achieve the max Z height with the stock keys. That would be an exception. His did not run those for long though. It soon received an SFA. Check out Quickbikers truck for more on that.
You mention a 265. That is just the width. If you can find a 265/70-16 or 265/75-15 that you like it should fit with a little trimming and a 2" body lift. That would be almost the same size as a 31x10.5-15.
Look around here. Don't be afraid to bring an old thread back to life. That keeps all the information together and makes it easier for the next guy who is searching for answers.