Slick 60's

Has anyone tried powder coating on top of POR15 rust prevention paint? I have an old oil bath air cleaner that I want to use, but it has some pretty deep rust pits in the crevices. I think the POR will pretty much fill the crevices (did a little test with a rusty bracket) but not sure what to put over it. POR15 is supposed to handle 600 degrees and the powder coating cure is only 475 degrees. Or would I be better off just using rattle can engine paint?

I don't think powder coat will stick to anything but bare metal.

I don't know...my power coat guy didn't say that was the case, he was concerned about the heat factor since the powder needs at least 475 degrees to cure. That's why I was looking for results from someone who had tried it.

I have had plenty of powder coating done over the years and we have always tried to get the metal as clean as possible typically with sandblasting.
I would think about doing a test piece first.

Grits por also sells a high temp coating thats suposed to be good to 1500. I put it on a set of headers for my 390. but havent had the option of testing it on the engine yet. I think its only available in silver or black, I got silver

Gritsngumbo

Are the pits where you can get to them to sand or file them?? If they are sand blast the part if you can and go buy a roll of acid core solder. Use a propane torch and heat the piece and apply the solder to the rust pits. Use sand paper or a body file a small disc sander or what ever you can to level the pits. This will fill the pits nicely and give you an all metal to have powder coat applied and will withstand the heat. Don't use the non lead based solder as it wont stick to steel very good.
I have used this procedure for rust pitting under windshield gaskets and the like. I use regular body lead tho because that is how I learned how to do it. I use body lead for most of my body work any way. I learned the use of lead when I apprenticed in a body shop in the early 60's. Giving away my vintage now but the procedure I outlined above works well.