Re: what is our trucks cam ??
I was already writing this so I'll finish. The more things you change that affect the VE of the engine (things like cam, heads, turbo, etc...), the more compensation the chip will need to have in it for these items. What I meant above ("you can get away with.....") was that, often times, there is enough of an operating margin in the stock tune to allow for an increase in certain items w/o having to redo the calibration. Go any bigger or farther out of the operating range and you'll start to see the tune suffer. The AFR will run lean/rich, the timing will want to be adjusted, etc...all of which can be remedied through a chip reburn (within reason...)
As far as how big can you go? There are 2 ways of reading that....1) - How far can I physically go? and 2) - How far can I go on this tune? Cam-wise, you can physically run up to .460-ish lift on stock valve springs (.500-ish on LT1 springs, and even higher on aftermarket and LS1 springs), but you will see the tune suffer for it somewhat.
My advice....set some goals and see what parts you need to get you there. Cams help our trucks, but a stock cam has been pushed REALLY far. Are you sure that you need/want one? Could you get by with stock? Do you just want a lumpy sound? Tons of questions to ask. As far as the chipping is concerned, with your location, I would stay with a proven combo unless you're willing to learn how to tune the stock ECM. This way you can order a "shelf" chip that will work with your combo.
So what are your goals?