The float valves Danny is referring to are also sometimes called "the needle and seat". The needle valves in Brostal/Solex (Kadron) carbs have no rubber and are a brass/brass seal. As such, they can tolerate almost no fuel pressure.
I'm a fan of getting the Webers, but you exchange one set of challenges for another in doing so.
Welcome to the Madness. Forewarned is forearmed.