Why on Earth would we want the F-1 to return? It was designed in the 1950's and does not offer particularly good performance. It runs somewhat reliably, but its sea level ISP is only 263, barely better than a solid. Even the Merlin 1D, designed to be a cheap throwaway gas-generator engine, has a sea-level ISP of 282, while the RD-170 with a staged combustion cycle has a sea-level ISP of 309 and slightly more thrust than an F-1. Due to its much greater efficiency, four RD-170's can put up much more payload than 5 F-1's.
But if they want to pursue the kerosene route, why not just go ahead and design a first stage with something like 5 F-1's or 4 RD-170's, then have that lift a hypergolic second stage powered by J-2X's or RS-25E's?