I think for the standard variety Weber intakes for medium riser head FE, there's one company that makes the casting for all the suppliers, Pierce, Inglese, Redline, TopEnd, etc. I don't know the company's name but that's the rumor anyway.
The one I bought from TopEnd in North Hollywood, CA was nicely machined, bolted right on and sealed up with no issues or gaps. I measured carefully and used feeler gages first to confirm.
The linkage that came with it, is positive and easy to adjust and is synched well so the carbs all open at the same rate.