Yes, Ford was somewhat late getting into OHV engines, but not entirely. After the War, under Henry the "Duece," they new they had to change. However, their engine production facilities were ancient, so they had to be overhauled & it was a big & expensive project. Don't forget that G.M.s new engines, for 1949, were made for the high & medium price fields, not the low price field. Chryslers first, 1951 was also for the high priced field.  Fords 1st OHV engine was the Lincoln 317 of 1952, (& in a brand new model, it preceeded to win the Carrara Pan-America Road Race, stock car division, 4 years in a row!) However, I've read  somewhere that Ford hoped to get the Y-Block into production for their 50th year Anniverary in 1953, but production difficulties nixed that. So they introduced the engine in 1954, and it was the 1st OHV available across an entire line in the low price field..The Ford/ Merc Y-Block should have held prominance longer than it did, but a series of bad decisions by Ford management &  smart moves by G.M., orchestrated from the mind of Z.A Duntov, and at least one or more "fast ones", pulled by their main competition, (the 1957 AMA racing ban agreement for one)  resulted in it fading from prominence, while the SBC became the "darling" of the small block crowd...               

Paul