\[\boxed{\mathbf{450}.}\]
\[1)\ \left( \sqrt[6]{7^{3}} \right)^{2} = \sqrt[6]{\left( 7^{3} \right)^{2}} =\]
\[= \sqrt[6]{7^{6}} = 7;\]
\[2)\ \left( \sqrt[6]{9} \right)^{- 3} = \sqrt[6]{9^{- 3}} = \sqrt[6]{\left( 3^{2} \right)^{- 3}} =\]
\[= \sqrt[6]{3^{- 6}} = \sqrt[6]{\left( \frac{1}{3} \right)^{6}} = \frac{1}{3};\]
\[3)\ \left( \sqrt[10]{32} \right)^{2} = \sqrt[10]{32^{2}} =\]
\[= \sqrt[10]{\left( 2^{5} \right)^{2}} = \sqrt[10]{2^{10}} = 2;\]
\[4)\ \left( \sqrt[8]{16} \right)^{- 4} = \sqrt[8]{16^{- 4}} =\]
\[= \sqrt[8]{\left( 4^{2} \right)^{- 4}} = \sqrt[8]{4^{- 8}} =\]
\[= \sqrt[8]{\left( \frac{1}{4} \right)^{8}} = \frac{1}{4}.\]