Finding a streetable transmission that can that hold up to the power and torque curve of even our base LS12 engine is more difficult than you might think. We put in a call to our friends at ATI and they are building us one tough TH400 with a full auto valve body that can handle the LS12 while retaining some street manners for the SEMA Camaro build.
Once power gets much past the 700HP mark finding a capable full auto trans starts to get difficult, which is one of the reasons we suggest our 717HP engine for street applications. Beyond that stepping up to a manual valve body starts to become a necessity with an auto transmissions and cooling and fuel system requirements also require some serious attention.
For those wanting to run a manual, we have been talking with Modern Driveline. They have a 6 speed package with a double clutch setup that will work really well on the street too.