It took me a couple looks to determine the seats for the antisiphon slugs had been left out of this proSystems carb, it had stuck brass antisiphon slugs in it that I drilled & pulled out to replace with stainless. One of them seized up so I pulled it all back apart, thats when I saw there weren't any brass seats and the slugs were sticking into the much larger hole. Luckily the same brass slug is used for press-in air bleeds so I drilled them to .060 and set them in place, good to go!
Theres a first time for everything I guess.