gasket is re-useable, its only rubber, but it will have stretched, you can push it in tightly and it fits and stays, then you have to watch it when you put the cover back on.
I had painted mine a red with high temp paint, but it looked a bit poxy, so i resprayed it in light blue, pretty much similar to V8Rumbles rocker cover, and it came up a treat. i sanded down the red somewhat, and then applied the blue enamel, and its much cooler than the red used to be after a thrashing, and it hasnt faded or pealed still looks perfect, mind you i polished it up with meguiers too.
watch when putting gasket back on, the rocker cover is sharp where the gasket is, poor finish (well on mine anyway) and i sliced a 2cm line thru my finger, and boy did it hurt!
originaly i paint stripped mine also, and it comes up a lot better, ad the original paint EF/L is quite coarse.
btw theres wrinkly paint you can buy now, spray it on, and it wrinkles up, but still sticks to the cover, and wont peal off. I reckon that would very cool!