If you're comfortable wrenching on your truck, then you'll probably have no trouble. There are some great carb builders on this forum that can help you.
I used a kit from NAPA to rebuild my '54 Rochester B.
>>> Label and bag each piece as you remove it. You'll thank me when you start reassembling!
See the overview of the Rochester carb in the 1948-51 Chevrolet Truck Shop Manual ...
http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0658.htmThen follow the step-by-step instructions in the section titled "Major Service Operations."
You may also want to check info in Rochester Service Bulletins ...
http://chevy.oldcarmanualproject.com/carb/Rochester/index.htm