Ive just bought a .58 cal Zoli muzzle loader and can only find .535" and 570" balls. Are these OK because I heard the balls were supposed to be .560".
The barrel specs are .578 land-.586"grooves and I was hoping I wouldnt have to cast my own.

It really depends on the land diameter of your rifle. You might have to use a thin linen patch with the .570" ball, but I shoot them in my .58, which has a .575" land diameter, and I use a .010" TC prelubed patch.

Use the .570 with .013 patch. Pillow ticking should be about right, and although tight to load, should work. I know things vary alot between the states and Oz, so pillow ticking here, may not be pillow ticking there. You'll only be out a box of bullets to try, and a friendly dealer may let you try the fit with a patch before purchase.