for castor set it all the way back towards the firewall (if there is a castor setting on this cc plate)
as far as the camber setting yea it would be positive if its all the way away from the engine..... before you tear anything off....measure the top of the shock nut to the inner fender(this will measure the camber setting). after the plate is installed measure the same distance to get in the same range camber distance as it was before.
and when the base line is all set and done get to the alignment shop and spend the 60 bucks. those 60 will save the life of your tires