[NewBayColony]

He is right about not splitting each gear. I doubt you will ever have a load so heavy that you would NEED to do that. Start off in low axle and that kind of saves your clutch. Splitting the top gear is usually all you need to do. The most you should have to do is split the top two gears. Most of the time you will only need to down shift the axle to keep your speed up. I have driven these trucks with 292 6 cylinders and you have to shift more but that 2 speed can keep you in your power band much better.
As far as the brakes go, I can't ever remember thinking they were not enough. Just make sure that they are adjusted correctly. Same for the parking brake. The lever that you set the brake with, the end of it twists to adjust it. When you get to work on it, back off the the handle in the cab all the way, then go under the truck and adjust it underneath so it's tight but not dragging, then you'll have plenty of adjustment from within the cab. The parking brake is located behind the transmission, on the drive shaft. You'll see that they too are a simple form of drum/shoe setup. When adjusted properly, they work great.