I blasted my frame and then painted Por-15 and when it came time to weld the new front end on, I had to GRIND the paint off.
To get into those hidden areas I used a small pump/spray plastic bottle (disposable) and it worked great.
I'm going to top coat the frame later with orange to match the body.
I've used Por-15 on lots of other stuff including a homemade trailor I haul wood with. The trailor sits outside all year in the woods and it still looks great.