"I says"

[Catherine Jagoe]

I am a translator with a question on verb morphology.  I’m translating a novel
set in Argentina between 1976-1998 from Spanish to English, for a British
publishing house.  There will be both a UK and a US edition, although initially
the book is scheduled to appear in the UK.  One of the narrators is a
prostitute from the provinces whose story is told in stream-of-consciousness
form, in highly colloquial Argentine Spanish with very little punctuation.  I
have tried to reflect this not only lexically but by occasionally using
non-standard verb morphology, such as “I says”, to reflect the chatty,
uneducated conversational style of the speaker.  The publisher has insisted on
standardizing not only most of the language itself but also argues that the use
of “I says” is inappropriate because it sounds like London Cockney dialect,
which would be inappropriate for a Buenos Aires resident from the 1970s.
I’m convinced that “I says” is not limited to Cockney, and that I’ve heard it
used widely both in the UK and the USA, but I have no documentation on that and
no idea of how to go about researching it.
Can anyone tell me about the distribution and usage of “I says”?  Are there any
other similar expressions that might accompany this usage?
Thank you.