Your reading is very close. Kaykhusraw III b. Qilij Arslan. Madinat Lu'lu'a mint, AH 664.
Obv. margin:duriba bi-Madinat Lu'lu'a fi sanat arba' [wa] sittin [wa] sittmi'at (was struck in the City of Lu'lu'a in the year four [and] sixty [and] six hundred).
Obv. center:al-mulk lillah (the kingdom [belongs] to God).
Reverse:al-sultan al-a'zam (the sultan the very great)/
ghiyas al-dunya wa al-din (help of the world and of the faith)/
abu'l-fateh Kaikhusru (father of conquest Kaykhusraw)/
bin Qilij Arslan (son of Qilij Arslan).
Compare here:
https://www.zeno.ru/showphoto.php?photo=227292The "extra letter" in your comparison is actually the tail of
fateh from the line above.