That is one lovely frame / cycle you got there Phil. I am a big fan of the gloss/matte silver finish (plated/anodized silver) for bicycle parts such as rims, stem, spacers, headset cups, seat-post, handlebars, crank arms etc as opposed to the anodized black alternative. I think they bring a highlight to any frame colour but especially high contrast like your black frame. Since all those parts of yours are already silver then I would finish the flat bar conversion with a gloss silver handlebar and matching seat-post. Although I prefer, my bike came with such parts black from the factory; a niggle but doesn't warrant changing them so I just put up with.
On the other hand, shiny silver parts do reflect the sun and stand out so might be something to consider if your aim is to use her often, lock up in high street locations and feel overall more confident she won't be a target. I suppose it will also depend on your daily business for her, example going to the cinema, locking outside and then coming back from the feature film to your ride home sort of situation. I admit I fall into this category where I feel the need to keep an eye on my bike at all times even during a short pit-stop. I think it comes to a point where one doesn't ride his/her beloved bicycle as often as the bicycle deserves. Safe to say that I should teach myself better to let go of the fear of losing. 'Lock up at your best, if she goes, she goes.'
The rims might of possibly came from the Thorn factory of different brand to meet pricing with the tougher sun rim on the rear maybe to better withstand pannier bag weight or another possibility the front rim braking surface wore out so needing replacing down the line. Who knows...
Best of luck with the rebuild/restoration. Maybe I will see you out riding her in the near future, assuming the previous owner was Cardiff based you may be local-ish to my area, Cwmbran.
Kyle
