I just stripped paint off my historical wainscoting exterior porch ceiling via a heat gun. Once stripped, I noticed the wood was once stained. I was told that over 100 years ago, people stained their wainscoting with tongue oil and nicotine So my question is, once I lightly sand the residue of the ceiling, should I spray tongue oil on the wood and leave it since the wood is already stained, or should I stain the wood all over again and then poly the wood?

Thank you for your time and patience!