Holley 870 street advenger - junk?

Maybe not the carb. OTH I dont trust any of these new carbs. And even old ones sometimes have odd things inside.
It wouldnt hurt, and may make you less anxious, to note the locations and measure all of the restrictions.
I think Mike and others on RFS forum have posted about finding odd calibrations in the street and truck avengers.

Typical idle feed restrictions on a 4150 type carb are around .028 to .038" dia with idle air bleed restrictions around .070" to .076" dia. Although I've seen smaller and larger used that's the typical range. .014" is way too small.