The red oil filter you show is a service replacement part. I will defer to others re which filter was used on the Cobra and the RLL-9 question, but the original 65 GT350 filter was painted black and featured a yellow Rotunda stamp. Images can be found by searching this site. But the red filter wasn’t original to the cars. (The filter was painted blue on the engine in 66).
That said, the black and stamped filter for 65 is otherwise the same as your red filter. Some folks have taken to repainting and stamping the red service replacement filters to mimic the black assembly line version. It’s not easy to do properly (ask me how I know) but excellent results are possible with the right combination of artwork, stamp material, technique, paint and obsessive determination.
FWIW, I will speculate that the rough paint on the end of your red filter is simply damage caused to the surface somewhere over the past 60 years.
Good luck.