I've had a go at this recently and didn't find it too daunting. I bought all new seals and gaskets from Mike Nixon @ motorcycle project and a small ultrasonic cleaner from a local car parts store. I only used genuine honda parts ( float needle valve and seats) most other parts can simply be cleaned, as they don't actually wear out. I kept all parts in a compartment box so each item went back to the same carb, used JIS screwdrivers only, and took a slow, methodical approach.
Yes, there is a small vent hole on the side of the carb bodies which I found while throttle cleaner fluid and running compressed air through all vents and jet openings - you ensure it's clear this way. Carbs are now clean and ready to go. BUT, I've yet to fit them and see if or how they run!
Fingers crossed!