Here is a pic of the line you need to block (right arrow)(left arrow points the the vacuum line you no longer need) Block that vacuum tap with something more substantial than vacuum line or it will rot though... I used a screw, then covered it with a rubber cap)... the other two small lines off the bottom of the carb, are float vents,... they go to nothing, zip tied to the frame, above the carb. They must be open, to vent air , and be higher than the carb...
Cal. model tanks, vent to the charcoal canister, US models vent out the cap...
If you don't want to change or modify your cap to vent,.. just make sure you have a hose attached to the tank vent elbow that goes up above the full gas level in the tank... You can put a filter on the end or not, it just has to terminate higher than the gas level in a full tank...
Otherwise,.. it will dribble gas...
...
If you are a fiddler, like me,... you can take apart the gas cap, and find the rubber plug in there that blocks the vent. Replace it with a BB... I can't be more specific, because I've never done it with a Suzuki,... but I've done it with a Yamaha... so, no guarantees there...
If you do it,.. you can then block off the tank's elbow vent.
If you don't,... that vent must be open to atmosphere, to allow the gas to flow...
Hope that helps...