I always, always, always, set the float heights so that the fuel level at the jet in each carb is the same. The manual instructions are fine for original components, but my car, like all of our cars, is many decades and hundreds of services from brand new, with many inexperienced grease monkeys’ fat fingered attempts at adjustment altering the shape and effect of the many parts that affect the fueling of SU carbs. Setting floats heights after checking the levels at the jet is a PITA requiring several attempts, but it is the only way to ensure that the fuel level is correct.
I’ve set fuel bowl height as measured by fuel showing the the three respective jets and she fires instantly (with choke), 30 seconds later choke off and she idles even on tach @ 1k but lumpy to ears and even at exhaust pipes. Used Unison tool to slow idle screws showing middle of tool.