I have asked for more info about the calipers. As best I can tell from the photos they looks to be Forged Superlite calipers. These calipers are all 4 pot calipers, take a 330mm rotor and can range in piston area quite a bit.
http://www.wilwood.com/CaliperList.aspx?subname=Forged Superlite://http://www.wilwood.com/CaliperList....orged Superlite
The calipers with the 1.62" pistons would have a piston surface area similar to Brembo f40 calipers (53cm squared). Anything above that would put out the bias of the brakes by quite a bit. The small 1.38" calipers would probably have a piston area too small (38.5cm squared).
This is just best guess as far as I can tell. I will update once I am given some definite info.