If you're looking for central counties of just two MSAs... easy... just look it up. The counties membership in 2023 MSAs is an excel sheet, here https://www2.census.gov/programs-surveys/metro-micro/geographies/reference-files/2023/delineation-files/list1_2023.xlsx (If anyone wants to use this sheet in a data analysis, you'd want to reformat it some.)The counties membership in 2013 MSAs is here https://www2.census.gov/programs-surveys/metro-micro/geographies/reference-files/2013/delineation-files/list1.xls
(Naming the files "List 1" is just Census's acknowledgement that these are the same List 1 as found in the OMB publications.)--T