[d.]

4 row is typically for a AA truck and the radiator shell is deeper to accommodate the extra depth. A common Model A passenger car or pickup should cool just fine with the standard 3 row core.
If 3 row core ain't getting it done, your issue is probably a clogged block or restricted tubes in the existing 3 row radiator core.
This might call for removing the upper and lower tanks and rodding the tubes.
A can of radiator flush won't do the trick.