That will work but you then supply 3 possible leak points, at the needle, gasket between the filter housing and carb, and the inverted flare where the fuel line seals.
I much prefer to check them with a large rubber hose fit tightly over the outside of the inlet seat.
Even with that said we haven't seen any leakers for quite some time now. About 15 years ago the suppliers sent out a batch of N/S assemblies where they missed the step in production that forms a seat and we had a LOT of issues. Had to take every single one out of the package and test them before we could use or sell them.
These days its extremely rare to find a bad one, and when one runs into this issue a quick/light tap with a steel check ball into the seat will usually correct the issue........
