Go with the 115mm brake, they will fit fine on the JJ. I have the 115mm brake on my AK JJ and I don't think that I had to bend the brake at all. I have been informed by a rep that their brakes will usually fit up to 10mm wider than the stated width, without needing to be bent.
Also I believe the 130mm brake FKS only comes in an 18 din version.