I've never taken a carb out of a box (I've had two Demons and maybe a dozen Holley's delivered that way over the years) and had it work to suit me - especially on a new application. Consequently - my 525 Jr carb doesn't have the same set-up it arrived with, and I'm fine with that .......some are not. It has some nice tuning features that I've not found on the older design Holley's.
What I found was .... the BG carb was very "tunable" (all of the Holley tricks and all or nearly all of the parts work) and the engine runs fine with it. The needle and seat parts it came with didn't like alcohol laced fuel and had to be changed to steel. It works well with the .130 Holley parts I put in there and it was an easy fix.
The carb seems to be sensitive to fuel bowl level - don't just try one and call it good. A very minor upward change (off of centered in the window) of my primary was the difference between a slight hesitation - and smooth acceleration.
Steve Metzger Tucson, Arizona