Maybe a sodium bicarbonate (baking soda) media blast would be a little gentler.Sandblast it.
AceMan is all over this.
Get an orbital sander and take that down to expose different layers of paint, all the way back to bare wood. It will take you 2 hours, tops, and it will be pretty awesome no matter what you find underneath.
You might need to take all of the tar layer off, though.
Sandblast it.
Sandblast yourself.
Anglegrinder...
I might go with the heavy strippers today![]()