IRS alignment setting for wide rear tires

[speedy]

hello i need help , i have dropped my irs back end by 1 spline and fitted a set of 1.5" lowered spring plates , the camber was -ve3" i followed the instructions and ovaled the holes in the rear of the spring plates using this method i have -ve 1.5 degree's of camber ,i would like -ve 1.0 degrees as am running 255 rear tires , because i have rotated the rear of the arms up in relation to the springplates the the a arms are catching the top of the spring plate just behind the top hole , this has left me with 1mm of toe in 1\2 mm each side i would like another couple of mm , i do not want to cut anymore material behind this top hole as there is not a lot there to start with and with filing the holes oval there is even less , any help or advice will be welcome or am i making a fundamental error with the method of changing the camber ,
cheers jon