There is a site you could try...they often turn up at autojumbles selling chrome top lamps etc..called GMS capri spares..sell all sorts of ford stuff

http://www.britnett.net/gms/

Selling amber indicators for £22 a pair...might be pattern though

I have in the past "re textured" plastic parts with a crackle finish by spraying them in primer and rubbing down with wet or dry to get them to a smooth finish and then spray them with top coat can take a few good coats of primer to get them smooth but worth it. There are often the black end caps on e.bay. (search on escort MK3 or rs turbo)

hadrian sell bumpers, again probably apttern

Hope this helps