it is correct that 84 chiv gives you 50% from EoO (same as before the change) BUT the question is:
do you need it?
I don´t know the exact numbers, but 74 won´t be far off, so if it will ruin
your template, getting chiv higher I would not bother.
One important thing: you need at least 80 chiv to have a 100% for consecrate weapon - not to cast it, but for it to work on each hit.