Truck motor should be okay at that power level for awhile on the bottle, transmission is a different story. The stock one was dying, it has a built one now but even still it has problems. 4L60E's are garbage.
My friend had a stock 4.8 in his 00 Silverado for YEARS, running 2 bottles a week, 150 shot, he blew alot of transmissions, never hurt the motor, even after alot of nitrous backfires. The motors in the cars dont seem to be as forgiving though.
I dont think he is gonna do much more with the truck, he just got an 02 Z28 a couple weeks ago.