Hi Fatcatmehmet,
The 180/230 grit might be a little coarse for flattening your other stones, and you don't know if they're flat. That's important--good hones are, as you're discovering, very expensive. If you try to lap them with a stone that is not flat, you'll wear them unevenly. You'll either lap a dish into the center, or thin too much off the ends. I really recommend against saving money on your lapping hone. The DMT ones are very flat, guaranteed.
There are different systems used to refer to grit. 1200 on the FEPA scale is the same as 4000 on the JIS scale, or the same as about a 3 micron particle size. But natural stones can vary a lot. It's hard to say what your TOS really is. You could post the question in the honing thread, and see what people think of it.
The commonest AFFORDABLE finisher people use is a Chinese natural water stone, with a grit around 12000 (JIS scale, the same as your Norton). People abbreviate it as the C12K or the PHIG (People's Hone of Indeterminate Grit). Here's a
vendor's link to that stone. I didn't see one like it at the site you're ordering your Norton from. There are also very fine Japanese natural stones, and antique German and English polishing stones, which can be VERY expensive. You might also consider a coticule in a couple more years.
You should post your question in the honing forum--tell what hones you're ordering now, and ask what people recommend for a finishing hone. The folks reading in that forum may not be reading in this one.
Good luck and best wishes.