Thought i'd share this as might be a useful contact for others wanting to convert their pre AI lenses.
I picked up a 200mm f4 for pretty cheap money locally, pre AI though so wasn't really going to mount on my D90..
Found this company below that had all UK Nikons conversion kits for these older lenses.
Paid £22 delivered and think it was the last one he had for this lens, so got lucky.
Saved filing the aperture ring down anyway which what i thought i'd have to do.
Very helpful and friendly service, id use them again.
Lens works great results look really sharp, have to get out with it over the weekend UK weather permitting...