Although I think -2.5 camber is enough to get by on, I do think -3 is ideal for track for our weight of car, especially on tires with soft sidewalls.
Please be the first to try and miss-match a set of camber plates. The only thing you will be doing is raising the vehicle but if you use lowering springs, you can bring that back down. You will have Extra droop travel as well. Using the camber plates at full NEGATIVE camber and using a eccentric bolt (SPC/Ingals) to dial out camber will actually give you greater wheel to shock clearance for larger rims & tires!! 17x9s with 255s hehe!
-- Buy lowering springs that lower at least 2" Try and find ones with machined flat tops. (read bellow for why)
-- buy the camber plates
-- Buy a set of the following but measure your shock rod diameter first.
Pegasus - Thick Nadella Thrust Washer - 2mm thick
Pegasus - Thin Nadella Thrust Washer - .8mm thick
-- the most difficult part of this is fullfilling the NEED of the needle bearing thrust washers which says they need TWO flat surfaces to mount in between. OEM like springs usually don't offer this which represents a problem and could/will sacrifice ride quality and integrity of the brearings.
GL