In this article https://arstechnica.com/science/2013/04/new-f-1b-rocket-engine-upgrades-apollo-era-deisgn-with-1-8m-lbs-of-thrust/ and in several answers on this site a modernized F-1 engine is referred as being planned to be used on the SLS.
What is the status on that, is that still in the plan and if so how is schedule and progress looking?
Edit Questions that prompted this: