81 kz1000 csr float bowl question

Im working on my 81 kz1000 csr and i pulled the carbs and while taking them apart i noticed the float bowl half covers a hole on the carb body..i included a pic...they are mikuni bs34s if im correct..the gasket doesnt seem right but when searching thats the only one i can find.

I'm not familiar with every possible variant of those BS34's but typically that passage is blanked off. You might want to remove the float bowl and probe the passage to see where if anywhere it goes.