[greg64]

I did exactly this on my 64. Based on 10 years of using por-15 prior to this task, I did a lot of experiments. My experience is that the best application is to sandblast first, then treat the whole part with Metal Ready until it has a chalky white appearance. Then wash that off with water and dry everything. When dry, start applying the por-15. It really sticks.

The peel off problem happens if the metal is shiny and smooth. There's no tooth for the paint to really adhere to.

I'd agree with the previous poster to follow por's directions.