Can you clarify what the "swivel adapter bracket" is for the UA874 in a wall-mount condition? How does it mount to the wall?
UA874 has a mount that is like a mic clip. UA874 will mount to the top of a mic stand that has a 5/8"-27 thread, or to a gooseneck. Check Atlas Sound for a large selection of mounting hardware with 5/8"-27 threads.
Mount to a wall: Atlas will have hardware that fits your wall mount requirements. Thread the UA874 on to the Atlas hardware.