Repair parts for internal seals of a fill valve are generally not generic...you'd need ones made specifically for that valve. If a toilet is not designed for dual flush, don't try to make it into one as it rarely works well. If your toilet can accept a replacement fill valve, I'd use either a Korky Quiet-Fill or a Fluidmaster and replace the whole valve. If you can get exact replacement parts for the existing valve, using those should fix it. Keep in mind that long-term use of chlorine products in the tank WILL destroy all rubber parts - not only gaskets but the flapper valve and maybe other seals in the toilet.