You have a couple different options. If you have the ca$h, I would go with a big brake kit up front like a Baer, Willwood, or SSBC. There is no need to do a brake kit in the rear unless you really want them to match. Your second option is to upgrade to a high quality rotor and pads. When I did mine, I didn’t want to spend $1K-$3K for brakes, so I ended up doing the EBC slotted and dimpled rotors up front with EBC pads in the front and the rear and kept the OEM calipers. I have been very impressed with these rotors. One thing you want to stay away from is any of the fully cross drilled rotors you will find on eBay or other places like that. Drilled rotors are subject to cracking when they get hot which is a bad thing. The only fully drilled rotors I would ever use would be the super high end Baer or Willwood set up. The EBC's are dimpled and slotted, so they dissipate heat very well, never any brake fade at all, and no brake dust, and most importantly they maintain their structural integrity from not being fully drilled.
The biggest risk you run without upgrading the brakes is that the extra weight of the wheel puts more strain on the rotors causing them to over heat, which then causes them to fade, which puts you in a potentially dangerous situation.
Not to mention, the GM rotors that come on these trucks are horrible. I would recommend everyone upgrading their rotors with or without big rims.
Here is a pic of the EBC rotors. Another option similar to the EBC would be Powerslot, but from all the research and asking around that I did before I did my brakes, the EBC's are the way to go. Hope that helps