Float bowl level, Using bowl level gauge Options

[scrz914]

I bought the float bowl gauge from partsklassik to double check my bench settings on the float and needle valve. I was surprised to see the level rise to the top. I shut the pump off before it overflowed. In reading the instructions I noticed it said to do the check while running the engine. I only ran the pump. Is there any reason to believe the levels would be different between running the engine as opposed to just running the pump? Also, is it possible that the needle valve is just sticking? I’ve heard even new needle valves can be problematic.
I have Weber IDA3C.
Here’s the gauge I bought. Not cheap. But it does come with different needle valve shims.

[scrz914]

I went ahead and checked the remaining 3 bowls and realized they wouldn’t overflow. That would be a major design flaw. I’ll have to run the engine to get accurate readings. Just gonna get it warm till it stops backfiring.
I did check psi from both sides of the fuel tee connection and it was 3 psi dead on.
What I’m really chasing is a temperature disparity between the left bank/right bank from readings at the exhaust ports. So I’m starting with the simplest most probable problems. I’m not really experienced with carbs so learning as I go.