Well, this could be interesting:
Rocket companies hope to repurpose Saturn 5 engines
Short form: Dynetics and Pratt & Whitney Rocketdyne have announced they intend to update the F-1 for the SLS. It appears that these will be for liquid-fueled strap on boosters to replace the five-segment RSRMs planned for the first two launches.
While a decent enough plan for this sort of thing, the reality is that for a booster rocket the size of the SLS, politics is more important than specific impulse in getting off the ground. A Delta rocket can swap out strap on booster rockets to suit needs, but the Shuttle spent thirty years promising advanced boosters,a nd never got anything fundamentally different than what it started off with. If SLS gets built, it may very well also spend thirty years using essentially the same configuration it stats off with.
Press release: