If you have never spent half a day scraping old Bitumastic off a floor, you just haven't lived a full life yet. Put it on your bucket list ! This miserable painstaking work is essential if you find any rust lurking beneath the material. In this case, it was just surface rust, but you have to get it all off in order to know. This involves a combination of paint scraper, chisel, wire wheel, and hours on your hands and knees. Then I coated the floor with POR-15, and it looked great.
A couple days later, the car sold without even leaving the trailer. I like to think that it is because of the work on the floor, just so that I can feel it was justified, but the truth is that the buyer did not really care, and it did not impact the price as he will put new floors in it. It is headed back to Germany.