I am neither an engineer nor a gunsmith, so take this for what it's worth.

The .450NE is a relatively high pressure cartridge - rated at 17 tons. That's many multiples of the pressure the Stevens 16b was designed to handle. I would not consider such a conversion. To me the debate would be whether the action could handle the .450BPE at 10 to 11 tons (also questionable at best).

I'm not familiar with that particular Stevens model; but at the same time, I'm not aware that Stevens made anything particularly noteworthy for its strength. Place a value on your left hand and eyesight, then make your decision.

Maybe somebody else would have a rosier opinion.

Curl