Mike and everyone at Pierce Mainifolds is super helpful and the new Webers are good........ but look at them carefully !
I got a bad one with a casting burr or gouge in the bottom of the emulsion tube well and it gave me a really bad time. I still don't really know what it was doing exactly but the emulsion tube & air corrector jet sat up too high and I suspect fuel from the emulsion tube was leaking into another part of the carb and activating the power valve.
Made me doubt myself as the car would perform perfectly...... and then smoke heavy and randomly and then stop with no ability for me to replicate the issue. Untold hours and a chunk of $$ trying to solve. I had never gotten a brand new carb with a problem like that !
Sorry for the tale of woe but, I think new parts are inexpensive nowadays and need a little more scrutiny than they used to.
In the end Mike replaced the carb and the problem was solved !