Why do you want to upgrade the brakes? Are you planning on towing, racing, or ????

To my knowledge, the only factory upgrade for the brakes is to swap on the brakes from a 3/4 or 1 ton truck. I think the heavier duty trucks had rotors 1 inch larger in diameter. There are several potential problems though: First, the one ton rotors weigh more. If you are thinking of a racing / high performance application, these may be to heavy. If you want larger brakes because you are towing or hauling heavy loads, the brakes off the heavy duty pick-ups are ideal. Secondly, the heavier duty trucks had 8 lug wheels instead of 5 lug wheels. You will have to buy new wheels and possibly tires with the switch to 8 lug wheels. If you convert the front end to 8 lug wheels, you will probably want to swap in an 8 lug Dana 60 or 70 rear axle so the wheels match on the front and rear of the truck. That way you will only need one spare tire. The master cylinder and brake booster are probably different between the 1/2 ton and heavier trucks as well.

Most guys are satisfied with the factory brakes on the 1/2 ton trucks. These were decent brakes for their era. Are you sure the brakes on your truck are functioning properly?