Early numbers weren't really lost because the serial numbers ARE the numbers. I'm sure basic sales numbers for V8's exist for '49-53, stuff I don't have, and serial number runs exist. The serials for '49-53 are not the engine numbers any more, but serials differ for 6, 8, and Merc and so could be totted up from all the different lots.
As I noted above, WWII and foreign productions add in some mysteries, but those do not involve large numbers of engines.
Spare parts also add in some engines...'32-48, Ford assigned serials to all engines completed to running order and tested, including industrials and complete replacement engines, but blocks and incomplete engine assembles for parts sales were not numbered. Probably a lot of flatheads carry replacement blocks that effectively add engines to the total...
So...some of the easier totals of the various groups:
Early 221: 6,925,898 PLUS 1942 civilian production, large WWII production, postwar English production...my SWAG would be 7,500,000 to cover all the loose ends...
Early 239: 2,374,315, probably pretty close to total as later production was small
V8 60, 1935--1940... 506,501 was the BEGINNING number for 1940, I don't have an ending# handy, but few were sold, then various overseas productions in small quantities. Probably absolute total well under 600,000?
'48-53 Fords and Mercs, I do not have much literature, but I think the numbers are fairly available out in the world somewhere. Serials of V8 series cars would do the job pretty closely.