I just completed the conversion on my TR3A three weeks ago. At this time there is only place that I found that has the conversion. There used to be a place in Virginia but his supplier stopped making them and he was trying to get them made in Taiwan.
British Parts Northwest gets them from a British company and they are mfg in Germany. The quality of the parts are excellent and the directions came in two languages, German and French. I called and they sent me the English version which was a half a page. The German instructions were about 10 pages.
A friend helped me and we completed the project. It would be a lot easier if the front clip and radiator are removed.
If you want to e-mail me with your phone number I will call you with more details. Now that it is done it makes the car handle like a real sports car.
Murray