Hello and Welcome.
My name is MIKE.
Im afraid it sounds like the crank pulley has worked loose and been running that way for some time... hence the marks - and the damage you mention.
The problem you have here is two fold... getting room to get at the end of the crank to do anything with it - and , what can be done.
Re the latter, it depends on the extent of the damage done... if its slight, it may be able to be repaired with machining tools... if its bad - its a new crankshaft Im afraid.
I suspect you will find too that the engine has to be removed to do anything with it - there is just no room Im sorry to say to do anything with it--
Let me know how you go..and / or let me know if you need anything further on this..~>>~~>>~ Meanwhile now at this point- Please do click on the "Exc / Ok rating" for me at this time.. "Thank you" in advance for that ... Note that you can get back to me anytime at all after doing the rating - it doesn't close you out -- Best Rgds, MIKE