All the above information is good. Here is some additional, Carbking recommended this book sometime ago. I have it and it is excellent.

"how to build and modify Rochester quadrajet carburetors" by Cliff Ruggles

Here is his web site;

http://www.cliffshighperformance.com/

I called him a few months ago to rebuild a Qjet. His turn around
for a rebuild was 6 months. I couldn't wait.

Here is another article on rebuilding Qjets. It will also tell you how to identify the carb by the numbers.

http://www.lbfun.com/warehouse/tech_info/fuel & intake/Q-Jet Tuning Paper.pdf

Hope that helps.

Larry

Ignorance can be fixed Stupidity is forever