Every honda head i think ive ever seen has some of the casting flash removed. It looks like someone took a cartridge roll and sanded the inner walls of the head at the casting lines? if so i believe its stock...
Are your retainers shiny? My portflow Ti are, not sure if they ALL are though. If their shiny, id say theyre most likely Ti.
Maybe you can mic the lobes to see if theyre bigger than stock? May have to remove the "cam bridge".
Like everyone else said, drop the pan and inspect the rods/pistons..A little bit of work but at least you can rest easy...