47-55.1 remove tar from underside of cab

[osaltyone]

Not sure why they did it, but looks like someone coated the passenger side floor of the truck with tar. It doesn't look like there was rust there from the inside of the cab in that area, but wondering how I can go about removing it without removing the cab.
Tried scraping it, but not so sure its the best option. Most of the floor is just light rust so hoping to hit it with a wire wheel and possibly POR15 since I have it on hand.