Wheel spacers, specially the generic 'J.C.Whitney' type, are not recommended on any performance vehicle, are illegal in most competions and some states for street operation.
It is important if you are seriously considering them to be sure you have properly engineered "Hub-centric"
type that bolt directly to the flange/hub and are engineered for your car. The common 'universal' type do not allow the hub to properly carry the load and transfer it to the flange and studs. The studs are designed to work in a clamping direction and not in a load carrying direction. They will quickly fail if the adapter allows the load to shift to them only. The hub/flange can also quickly fatigue and fail if the load is leveraged beyond it's bearing or structural design parameters.
I have worked on many off-road applications that used engineered spacers/adaptors and they perform well, but still have seen failures.
A common well engineered off-road type is - http://www.wabfab.org/products/wheel...eelspacers.htm
- but I don't remember them selling any 4 3/4" bolt circle adapters. Contact them for info.
You can check with a good supplier of custom wheels, like RONAL, as they often supply specialty adaptors for their wheels to some applications. You would need a set of 5X120.65mm (5X4 3/4") spacers for a Camaro. Don't know where you are located but here is a list of their dealers - http://www.ronalusa.com/
Any of these require special attention in properly torqueing them into place.
Remember that no matter how well engineered an spacer/adaptor is - one bad mechanic with an impact wrench can ruin your day ...
(Edit) I hope you don't take this that I endorse spacers/adaptors for the street - I don't ...
There is another post linking to this video - http://www.youtube.com/watch?v=UzhkqzDKleA
- showing a spacer failing on launch during a drag race (go to 0:40 on the video and look between the car and the rim/tire)