Does anyone know the exact dimensions for the metal panel inside of the Madcatz te2 fight-stick?
I do not have this information.
I am making a cold rolled steal panel with the default Hitbox(most efficient) layout for the TE2.
I need:
-The height and length of the metal panel
-Screw hole size and placements on the panel
-Ways to find out this information.
-Radius of the corners on the panel
-Corrections for buttons placement on Hitbox buttons (Official Layout)
Take your stock panel off and measure it 
I already have thank you.
Looking for confirmation
It sounds like you already have your measurements.
Honest truth is most the people that has already those specs are going to be ether unwilling or unable to confirm your measurements for one reason or another.
I honestly would not trust some of those very same people to give you good figures.
Outside of stick art templates, the only way you going to get confirmation is make a test fit. Make a dummy panel out of a cheaper material (like some good poster board) and test that fit your self.