Elo's Untitled GMs

Commenting on FIDE's first award of GM titles, limited to players living in 1950, Elo wrote ('The Rating of Chess Players Past and Present', 4.23),

Death came too soon for some of the strongest players in history, who remain unrecognized by the international titles carried by other players, often weaker, sometimes even older as well. But objective data were not available in 1950 for any titling, normal or posthumous. Subsequently, however, the data have been developed, in the study reported [later in the book], and the reader may now examine the roster of the untitled dead. Listed below are 24 great players, contemporaries of those on the first GM roster, who surely would carry GM titles had the current regulations been effective during their careers.

2650 Steinitz, Wilhelm; Bohemia (1836-1900)
2570 Charousek, Rudolph; Bohemia/Hungary (1873-1900)
2530 Walbrodt, Carl A; Holland/Germany (1871-1902)
2530 Mason, James; Ireland/USA (1849-1905)
2630 Pillsbury, Harry N.; United States (1872-1906)
2600 Chigorin, Mikhail; Russia (1850-1908)
2600 Schlechter, Carl; Austria (1874-1918)
2520 Marco, Georg; Austria (1863-1923)
2570 Blackburne, Joseph H.; England (1841-1924)
2530 Burn, Amos; England (1848-1925)
2570 Teichmann, Richard; Germany (1868-1925)
2570 Janowsky, David; Poland/France (1868-1927)
2550 Reti, Richard; Hungary/Czech. (1889-1929)
2560 Gunsberg, Isidor; Hungary/England (1854-1930)
2610 Tarrasch, Siegbert; Germany (1862-1934)
2615 Nimzovitch, Aaron; Russia/Denmark (1886-1935)
2720 Lasker, Emanuel; Germany/England (1868-1941)
2725 Capablanca, Jose R,; Cuba (1888-1942)
2530 Rabinovitch, Ilya L.; Russia (1891-1942)
2560 Spielmann, Rudolph; Austria (1883-1942)
2570 Marshall, Frank J.; United States (1877-1944)
2520 Petrov, Vladimir; Latvia/USSR (1907-1945)
2690 Alekhine, Alexander; Russia/France (1892-1946)
2530 Sultan Khan, Mir; Pakistan (1905-1966)

I've added the five-year average that Elo calculated for each player. The list is sorted using Elo's order, according to year of death. There are several names on the list who are not usually thought of as GMs. Elo continued,

An all time list of 197 untitled greats appears [in an appendix]. It includes 45 players who held five-year averages over 2500 and another 87 over 2400, meeting today's GM and IM requirements.

I counted 47 players with GM ratings, but I'm not motivated enough to investigate the discrepancy. The 23 players with ratings over 2500 who were not on Elo's list of GMs were as follows.

2690* Morphy, Paul; United States (1837-1884)
2600* von der Lasa, Tassilo; Germany (1818-1899)
2600   Anderssen, Adolph; Germany (1818-1879)
2600   Zukertort, Johannes H.; Poland/England (1842-1888)
2570   Kolisch, Ignatz; Hungary/Austria (1837-1889)
2570   Neumann, Gustav R; Germany (1838-1881)
2560* Junge, Klaus; Chile/Germany (1924-1945)
2560   Mackenzie, George H.; Scotland/USA (1837-1891)
2550* Dubois, Serafino; Italy (1817-1899)
2550   Paulsen, Louis; Germany (1833-1891)
2540   Weiss, Max; Hungary/Austria (1857-1927)
2530* Petrov, Alexander; Russia (1794-1867)
2530   Winawer, Simon; Poland (1838-1920)
2520* Staunton, Howard; England (1810-1874)
2520* Harrwitz, Daniel; Germany/France (1823-1884)
2520   Forgacs, Leu; Hungary (1881-1930)
2520   Englisch, Berthold; Austria (1851-1897)
2520   Lipke, Paul; Germany (1870-1955)
2510* Löwenthal, Johann J.; Hungary/England (1810-1876)
2510   Mattison, Hermann; Latvia (1894-1932)
2510   Ryumin, Nikolai N.; Russia (1905-1942)
2510   von Bardeleben, Curt; Germany (1861-1924)
2510   Lipschuetz, Samuel; Hungary/USA (1863-1905)

They are sorted by descending rating. Elo added the '*' to indicate that 'Data covers period of active play'.