hi,
I have skimmed the 4 pages of replies so please forgive me if i missed anything already mentioned but i wanted to add a little here as i went through a bit with my 79 and thought it may be helpful.
I too converted my front lights to halogen, i basically binned the sealed beam lights and bought a standard mini unit that took a halogen bulb, making sure i got the version with the small side light attachment underneath the main bulb. This was a simple swap to change the running/driving lights from the front lights to the sidelight bulb that pushes in to the mini headlamp unit sidelight socket (hole). as part of the mini lights i seem to remember ordering at the same time, a small sidelight bulb holder which was rubber and pushes in to the small hole underneath where the main halogen bulb clips in. This left the front driving lights with only the indicator operation left. When i was rewiring the indicators or was trying to get an orange bulb to fit, something snapped off and so i drilled all the way through the plastic and glued in a metal bulb holder. (this kind of thing
http://www.autobulbsdirect.co.uk/Bulb-Holder-BA15S.html) This worked really really well and i now have reflective silver indicator bulbs that are produced by phillips and bought in clas ohlsen croydon. this kind of thing
http://click-parts.co.uk/content/chrome ... -bulbs.php
As for the rear of the car i was pretty fortunate as my 79 has orange lenses for the indicators. However after 8 years of MOTing the car, it failed last year on not having a rear fog light. as i do not like spoiling the lines of the car with a fog light off the rear bumper i checked on the internet for the exact year requirement for one. As far as i remember it is mid 1980 that is the required year for having a fog light on an imported car. so i printed it out and took it along to the retest. that was the only time i have been asked, this year it passed with no questions.
You might also want to double check what year of car you are required to change the indicators to yellow/amber, you might be lucky and be ok with red lenses. Also i have heard that some people put green indicator bulbs in the red lenses and it makes it a lot more yellow. that could be worth a go too :-)
Good luck with everything, it is a very pretty car :-)