hi djgeorgie -

i have a kodak 3a folder that belonged to my grandparents ..
i don't know if it is the same one you have or are looking at ...
the lens on it is an ilex 170mm .
i don't think you will have trouble focusing at infinity
since the long end of that roll film format is 5.5" it will have
an illumination circle of at least 5.5" in diameter.
so it will probably "cover" and give you a tiny bit of movement
before it vignettes ...

you mention the camera+lens are cheap, sounds like the perfect use of the lens
that is, if you can't find a 2nd 122 film spool and roll your own ...

have fun