Surrey Mustang
One of the specialists I have encountered who I found to be a very reasonable chap is Surrey Mustang.
From what I have read they seem to be a good reputable company. He has answered some of my questions on the Mustang forums without pretending that everything is a state secret like some service providers do.
Surrey Mustang is also the manufaturer of the rear light units that have been converted from US spec by replacing one of the reflectors with an orange lense. That is discussed on the rear light units page.
If I needed to use a specialist for anything, I would use Surrey Mustang as my first choice.
The website is here: Surrey Mustang
