I've pulled the top cowl vent off my 54 Chev 3100 and need some input on painting the underside. It appears that it was originally galvanized and parts of it including the screen are showing light rust. The top side paint is good so I don't want to have the piece hot dipped. I was thinking of using a cold galvanize spray but after research I don't think it will hold up. Any thoughts on paint vs powder coating. I'm also looking at POR-15 gray rust inhibitor for durability. I've attached a Classic Parts vent just to clarify the part. Any input is much appreciated. Thanks

http://www.classicparts.com/1947-53-Top-Cowl-Vent-Assembly/productinfo/34-301/#.V1IY7eSgRAM