Unless you are going to fire full auto you don't really need a break on the weapon. The slant break on the AK is there to keep it from rising so much in full auto fire. If you really want a break on your gun get a pin on one. Threading the barrel can cause you problems down the road with folks like the BATF. It is not worth it. THe Mak 90 shoots fine without any thing on its front end.
Remember also if you do thread the barrel it has to be left hand threading. Threads are reversed to what we are accustomed to. You screw the break on counter clockwise on a AK. If your threads are the least bit off the break will not be on straight and you may shoot it off the end of your barrel. This happened to a guy we knew at our range.