Stagger jetting question

Generally almost never does a carburetor jump out of a box and onto a car and run perfect...
But never say never LOL...
It actually happened to me yesterday for the first time in my life...
We broke in a mid-60s 327 for a customer's 65 Chevelle on an engine stand with a known carburetor. Yesterday we got it ready for a test drive and after setting the timing the dual AF gages were reading just about perfect... I checked this brand new 1406 carburetor that we pulled out of the box and it was out 3/4 of a turn on both adjustment screws. I had to turn the idle up... Afterwards I tried to make some adjustments but nothing made it run better so I left it where it was...
I really think that these kind of 350 327 Chevys were what these were built around anyway so I guess it is possible I just never seen it before.