C6 filled tube plug

I've got a c6 that's freshly been built (reverse valve body, rollerized etc.) and it has maybe 200 feet on it .The trans has fresh redline fluid in it and was wondering what to use for the filler tube plug because I want to change the converter and don't want to lose the fluid  or bathe in it! If someone knows what to use of what they ship with it in the fillertube it would be much appreciated. !