Smaller primaries=better throttle response, and higher total CFM=better top end performance, and the Q-jet has anything you'd want to put on your truck beat in both of those categories, unless you went with a 500CFM aftermarket carb, which would still limit top end.
Listen to everyone else, I've never had an incline induced problem with my Q-jet, (nor anything else short of a temporarily sticky float as far as I can tell) and it performs admirably for being almost 30 years old. (of course I "rebuilt" it about 2 yrs ago)
You can't beat going to the store and rebuilding it for $20. If it's a high mileage unit and the truck hasn't always been well maintained, (regular oil changes, etc) you may want to go through it, and *might* need the primary throttle shaft bushed. My '83 had an idle that would vary every time I came to a stop, and it was because it needed bushed. No big deal, theres a place called "carbs unlimited" up here in WA that can either sell you the bushings to do it yourself if you are so inclined, but if not, I think they will bush it for like $40. I know thats getting kind of in depth and outside of what you asked, but it might head off some other questions you may have, and let you know that if you are having problems that might be carb related, they shouldn't be hard to fix.
Theres a reason GM used the Q-jet from 1965-1990, it works!
