I'm looking for a couple of these for the rear of my car ..... any ideas guys? Here's a pic
Rescued attachment reflector.jpg

Would it not be possible to fit some long rectangular ones and chop the ends off?

Possibly, except that they will lose the nice moulded edges and may look like they've been modded - worth a look though.
So the next question is ' where can I find some long rectangular reflectors? '

Dont reflectors need to be mounted a particular way up to work? I know the ones i have are distinctly marked TOP. You can flip them 180deg tho...

Good point - but I am sure I've seen this shape used on a tin top so I am hoping I can get one designed for the angle off the shelf.
Unless I can get away with the 'top' being 'nearly top'

How about the bottom of THIS Page
Or this one it says they're universally mountabubble!!Reflectors

don't forget the radius rules my supposedly SVA compliant ones failed and I had to get some more to pass.