To use the "actual" AK-74 brake you need to swap out your front sight assembly for an "actual" '74 sight unit as well.
The male threads are on the front sight tower assembly, not the barrel. It will require some minor WECSOG to remove the old sight group and swap in the new.
Try KVAR, they list them, but they're often out of stock, and remember you'll need both pieces. For a SAR-2 you'll need to order Romanian for both parts.
The conversion to real '74 brake is controversial because the '74 brake uses a size and type of threads unlike any other muzzle device or flashhider, therefore many people have the opinion that it is not necessary to pin or weld the brake (since a banned muzzle device could not be mounted). Some people are also concerned about the legality of adding an additional imported part on a "parts count" rifle.
The real deal military sight and brake conversion is by far the best, and coolest way to brake these rifles. If you wait 'till next year and the AW ban goes away, I believe you can install the front sight with bayonet lug intact (cool!) otherwise it will need to be neutered.
There are detailed instructions readily available on the net to complete the minor gunsmith work needed for the conversion.