If you find that you have drilled to large an orifice in the choke pull off you can solder or braze it closed and try again. In fact it may be easier/faster to just drill it out completely then soldering it or brazing it closed as it's easier material to drill out than the metal housing material is.
I had the original factory quadrajet on my 72 c10 for years. I researched so much info about quadrajets it's crazy. I got really comfortable with taking it apart and cleaning it and rebuilding it. At first it was a nightmare because I had no idea how they worked or what was even inside. Anyways, long story short is I had to replace it. I learned that the main body casting of the carb had tiny hair line cracks in the venturi booster walls where the vacuum chambers are for the manifold vacuum signal port on the passenger side of the carb.(directly behind the choke pull off canister.) My truck ran great for about the first hour of driving. Then it would have a weird kind of hunting idle speed and it was leaking fuel into the vacuum chambers that it eventually leaked fuel into my distributor vacuum advance canister and rotted the diaphragm giving me both a vacuum leak and a malfunctioning vacuum advance. Oh man, it took me literally months to figure that whole mess out. It's to bad because I really liked my quadrajet. I actually miss it.
Another thing to check is the power piston spring tension. There is a way to measure the spring rate based on inches of vacuum. It's similar to the step up springs in an edelbrock. You want a stiffer spring so that the metering rods lift up out of the jets sooner(higher vacuum signal) vs. Later(lower vacuum signal). of course you need to match your timing curve in the distributor to the fuel demand of the engine and the flow of your carb. Fun stuff once you get it all dialed in.
oh, one other thing I found out with my quadrajet is that they dont really like having any other fuel filters inline. Only the small paper one inside the carb body. They are finicky carbs and they know what they want and what they need. As long as your tank/pickup/fuel lines are clean. You shouldn't really have a problem just running the small filter inside the body. I didnt have any problems with mine. But it didnt like a filter between the pump and carb inlet. That's for sure.
You want 7/8 of a turn of preload on your secondary butterfly spring tensioner. That's as soon as the spring arm contacts the carb body 7/8 turn more and lock it in with the set screw.