Yes, your idea is an A+ in creativity.
Just a few other examples beyond Beene of how long it took for players to become GMs:
- Charlie Gehringer: Retired = 1942 then GM = 1951
- Eddie Collins: Retired = 1930 then GM = 1933
- Hank Greenberg: Retired = 1947 then GM = 1951
- Ruben Amaro, Jr.: Retired = 1998 then GM = 2009
- Kenny Williams: Retired = 1981 then GM = 2000