I didn't have access to POR-15, just used a WallMart brand of 'paint' that converts rust to primer. Used my grinder with a wire cup wheel to knock off the larger areas of rust in the floorpan. Wear a resperator in a well ventilated area, as the conversion stuff has fumes and besides, ya don't want rusty lung or whatever you get from rust/old paint, when you grind it off. Goggles as well, and yeah, I used a half box of rubber gloves (medical) between the rust converter and the herculiner. Did the entire inside, but my carpet had already been stripped out before I bought the '89. Dunno about POR-15, but with this conversion stuff, you want to use a seperate container to pour it in, not dip out of the can, as that contaminates/deactivates whats left in the can, if you want to use the rest of it later. I really like the way the herculiner turned out..but wear gloves..takes about 2 weeks for it to wear off yer skin..and the fumes are pretty powerful.