Carb tuning is an art. It is a balance between mixture, and the idle speed adjustments. Add in multiple carbs and now you have to balance them too. Plus get the throttle rods connected back up after adjustment. Be gentle on the throttle disconnects. It is not a matter of all of the mixture screws needing to be 1.5 turns. One may be 1.7, another 1.9, and the other 2.0. Wear, over tightening, and some design differences account for some differential in the number of turns, so don't get hung up on it. I usually prefer to start on the rich side, and turn them leaner (IE: start at 2 turns, before ever starting the engine). You will hear the engine RPM's increase as you get leaner, until it quickly falls off as it gets too lean. (A good tach is very nice to have too). Being ever so slightly rich at idle is better than too lean. Trying to hit the stoichiometric balance at 14.7:1 is ideal, but next to impossible without a wide band O2. Plus carbs just aren't that accurate.
A tool like the top one shown sucks. Trust me I own something similar. A manometer is the best tool for the job. Total cost should be less than $5. I could walk out in my garage and build one for free, the parts are that simple. I built one a long time ago for doing motorcycles, and they work great. Google "Building manometer" and all the information you will need is available.
Some carbs do not have the fittings already installed and you might need to install some. Just plug them with a rubber plug when finished. There should be a flat spot to drill out if there are not any. I keep brass tubing (Along with stainless) in my tool box for doing just such adventures, and get them from old broken car antennas. I have bought a few different sizes too. You just never know when you are going to need to sleeve a fitting or make something. Part of fixing stuff, is some times you break stuff
I have seen folks use welding tips too, which create a nice restriction. Use your imagination.