Hey Ash, A very good epoxy primer, which is available here in aus. is Intergard 269. This stuff works very well and a lot of guys, including myself use it underneath the car to copy the original red oxide coating. Its used in the marine industry so resists a lot of moisture.
http://www.international-pc.com/products/info/Primers/Intergard-269.aspx
Cheers, Neil.