i am afraid there will always be a smartass coming up with an inadequate answer and boasting super confidence to his believes.
But if i had to decide without time to look in the books etc, I wouldn't do it. Normal N1, period.
Maybe there is a note somewhere but I definitely don't remember it. I think the ATM for reduced N1 is only allowed along with using an approved data tool for runway analysis.
It has been a while since I used a Boeing QRH but I think it only provides for weight you can accommodate for the specific runway that day. I do not recall a chart that you can use to derive the ASDA with a different N1, let alone doing wet V1 reductions for the specific runway length.
By all means, runway analysis is required by the operator (for all his types used) in order to be authorized to operate at a specific airport. Someone referred to it earlier, all approved airports in an OM Part C. Correct me if I am wrong.
Just my 2c.