from what I have heard, weber carbs are supposed to give you higher performance

 

The Weber downdraft is not all that high performance. I know a guy that ran those then switched back to SU's. He said there wasn't really any big difference bewteen the two on his stock L24.

But, he had heard that fuel can puddle up in that lower curved intake adaptor as the fuel mixture goes down then curves back up.

Weber sidedrafts are very high performance.

I run a single Weber downdraft just like yours on my Datsun 4-cyl engines. Those are great little carbs for that application. Good torque and economy.