Yep, I'm familiar w/ all of the above first-hand. I've also owned a Race Demon RS 825 that came w/ the gold 1.500" venturi sleeves I kept as spares. As I received it from a "carb specialist" with whom I will never deal with again -- and not likely you would have ever heard of him or his business name -- the so-called "tested and ready to go" carb had a number of issues that I had to deal with, including sending some parts back to BG (they were still open at the time, but not for much longer) that should have never been let out of the factory in the first place. Even that didn't really correct the issues, since they simply "re-machined" the same parts, rather than bother to send any better replacements. And that was the last time I ever put any $ in the pocket of BG while Mr. Grant still owned it. I started thinking BG might just as well stand for "Barry's Garbage" after that experience. (Any of my carb parts that still have the "BG" logo I tell people it stands for "Brad's Garage". )
The other issue w/ the boosters that aren't machined properly at the entrance (not tapered and/or not on center) is those are typically the same ones that can't be aligned properly with the venturi: simply junk. Those are what came with my Race Demon RS and were worthless. At that time it was already difficult to find NOS (New Old Stock) boosters from the earlier production runs that were useable. However, I probably got lucky and managed to locate a decent set of .160" downlegs which I installed in that Race Demon RS before I sold it later on.
I dealt with the protruding booster end & retaining nut issue by surfacing them "just enough" to only stand proud maybe .025" - .030", and then using a thicker & softer (more conformable) metering block gasket that would seal up properly. Yes, I also found out on the dyno what happens when your gasket doesn't have enough crush to seal around the entries to the boosters sufficiently when they stick out like that. The ones that do crush enough are the original red Demon and the blue Holley; you need to check if those gaskets' passages from the angle channel to the booster entrance need to be opened up to not block the entrance w/o being too big and leaving the retaining nut surface exposed. If you can install one, remove it, and see the full imprint of the retaining nut and booster entry in the gasket, you should be good. The newer MP-15 and similar materials don't have enough "give" to work with this situation.