Periscope vents

Hi all I am fitting my scoops now I have IVA ..... whats the best way of fixing them .. I know on the originals they have fixings on show .......... Are the pop rivets or self tappers ....... or nuts and bolts SS of course ...

Thanks all ...John

Brian Stewart
Have seen both stainless screws with nuts and pop rivets on original MKIIs.

I am using stainless countersunk screws with nylock nuts for mine.