I've ordered a halogen conversion set from Mini Academy to replace the dismal sealed beam units. Unfortunately fitting these kind of headlights with the original back bowls would mean that I'd have to go through this entire strip down again just to replace a bulb! I hadn't realised this previously but thanks to a well timed thread on the Club Triumph noticeboard I discovered a solution. Thanks to 'phil866' who suggested the 7" open back nest set from Stafford Vehicle Components!
That's as far as I've got with the lights so far, but I have spent a little time fitting the alloy alternator mount that I bought from Canley Classics about 6 months ago. There was very little drama to report fitting it other than the fact that I cut my hand on a stray piece of glass that was hanging around in the garage! Just out of interest I weighed the old iron mount (575g) and compared it to the new one (225g). That's a saving of 350g! Very nice!