Many aspects of engine production changed during the Model A production cycle. Elsewhere is mentioned the "burning in" of Model T engines, a practice which continued in probably similar but lesser degrees as Model A engine production climbed.
Ford pioneered "surface finish" requirements and one of the complaints I have had about modern crank journal grinding is that it probably is not being done as "fine" as was done originally by Ford. Rather modern grinds are centered more around pressurized lubrication and lifting the crank away from the bearing surface by hydraulic pressure. A lot less requirement for surface finish: only need surface finish smaller than the average hydraulic film/bearing clearance.
The original Model A babbit/crank relied more on "hydrodynamic" lubrication - which is a sort of "boundry lubrication" which does not preclude the parts rubbing together, nor eliminate it largely as is found in pressure lubrication. Rather improved surface finish was used to ease the interference in - and eliminated by degrees the "burning in period."
Hence with "rough" cranks a tendency today for rebuilt engines done with babbitt to NOT last as long as they did when originally done.
My Model A mentor Arnold Goff commented that he thought a typical Model A engine life today was 60-70K miles. He put a lot of this to "no air cleaner" - but roads today are measurably cleaner than they were "back in the day." And air filter DO exist.
It would not surprise me to know that Ford finished cylinder bores "differently." As explained. And with good reason.
We've all seen the engine/motor/generator breaking-in stands used both on the Model T engines and later adapted to the Model A. Some have claimed the burning in step was eliminated completely late in Ford 4 cylinder production and the stands became test stands in fact.
Joe K