Hey Nacho, Not sure what you mean by BB and in relation to the heads you posted??

Whether they are present depends on when the heads were made and for what engine. See for example: 1973 Chrysler Clean Air MTSC, Air Injection

As far as the purpose, Pacnorth has basically covered it. The air injection into hot exhaust helped consume unburned hydrocarbons and also reacted with CO.
For Chrysler products, cats came later.

You're lucky. On my first engine install, I didn't notice them until after firing it up. The guys in the exhaust shop pointed them out. Not much fun tapping and installing the setscrews afterwords but it was a learning experience.