10char limit
3 options for you…
I use the classic casting bar one
https://www.curseforge.com/wow/addons/search?search=classic+cast
Only 3 i have come across that is ONLY for casting, otherwise you can try CTMod… which has several addon parts…
READ the description page before you DL and put them ALL in… for CT I use the Buff, mail, and map… I believe the CT core has options for the casting bar by default…
Everything stays blizzard default with this mod UNTIL you make your own changes…
10char limit
your more then welcome… Hope it works for ya 
we all have our own way of setting it up