They typically run the Dyno test is ran in direct drive, which ever gear that is in the transmission.
It is drive/3rd in the non-overdrive models.
Third in the 700R4/4L60 and variants.
Forth in the 6L80's as both 5 and 6 gear are over drives.
On my tuck the tuner used 3rd gear (4L60E) and the speed topped out at 130mph at 6000rpm with 3:73 gears. I had no driveline issues. I have a one piece driveshaft.
You can use this calculator to figure it out for your truck.
https://purperformance.com/p-29669-rpm-calculator.html
With your combination the drive shaft speed will be the same as the engine. Lets say 6000 rpm like mine. The rear wheel speed will be much higher because of your higher differential ratio (3:08) Tire speed will be close to 150mph.
You will want good tires. Any decent tuner will limit the engine/tire speed to your specification.
Good choice on the cam, perfect for the 4.8L. I always pick out the camshaft I want and purchase the next one down. It seems to work out better that way.
Tuners will reset the full throttle transmission shift points. An important feature for drive-ability. That way you can use the power where its made.
Cheers