Marlboro
there is no 'exact' all-engines relationship btwn EPR and N1, because every engine has a slightly different relationship, that's why you need EPR trimmers. And even then they will differ within the tolerane of each trimmer, but not too much. Suggest you work out the best EPR for the PW engine, not the N1. We have a lot of ex-GE jockeys with us (RR EPR fleet mostly) and they can confuse things by seeing N1 splits for a given EPR and write it up as a defect, when it's perfectly normal.
So consider using EPR if you can, or things might get confusing.
Regards,
N1 Vibes