sorry madone i couldn't reply. 8valvesgood here, changed to broadband and lost all my accounts. You can pick fuel filler necks for as little as ?30.
IMO if you can't get hold of a stainless steel MK1 fuel filler neck and if your a DIY man then buy a MKII metal fuel filler neck more common and cheaper. and has heavier gauge material, double the thickness. The downside is you have to cut the pipe and fit two rubber sleeves instead of one to obtain the angle to mate it to the tank, all the fixing holes and positions are the same though.
if you do buy a pipe you need to buy a new rubber sleeve to mate it to the tank and you will need a new rubber gasket to fit at the top as the old one will be long gone. You can reuse the black circle that covers the screws underneath the petrol cap.