I'm coming late to this discussion; sorry about that, but I was just directed here by someone who had some questions about the matters being discussed.
I'm not sure how Mr. Dalton arrived at the idea that it is beneficial to remove the bulb shield when installing the halogen bulbs. It is not! The bulb shield does a much more effective job of blocking upward stray light than the blacktop on the bulb does, and the bulb shield does this helpful thing without blocking useful or usable light. There is no benefit to removing the bulb shield; all you'll do is create more glare (for other road users) and backdazzle (for yourself in rain, fog, and snow). Definitely leave 'em in!
Original R2 headlamp bulb wattage was indeed 45/40 (high/low), and halogenisation bulbs are available in that wattage, (
http://store.candlepower.com/48-121.html) but the standard halogen H4 wattage of 60/55 on the P45t base is also available as p/n 48884 (
http://store.candlepower.com/48-884.html), and the wiring in these cars, if in good condition, has no trouble handling it.
The 5w BA15s-base clearance lamp bulbs are easy to find. Their international type ID is W5W, and you can often find them locally in a plain ol' parts store as a p/n 5007 or 17125.
As for the original 18w BA15s bulbs used in the front & rear turn signals, the brake lamps and the reversing lamps: these functions can safely be made 60% brighter by substituting a P3497 bulb (
http://store.candlepower.com/p3497.html).
An H6W halogen 6w bulb as mentioned by Naj is too bright for use as tail lamps; you don't get the necessary intensity contrast between the tail and brake functions. Also, their filament isn't in the right orientation to work correctly with the optics of the tail lamp, and there's also the nuisance of having to grind down one of the index pins. A type 3886x (
http://store.candlepower.com/38xefiinpala.html) is a better choice for the tail and parking functions. It's a 6w Xenon-filled bulb that has the correct index pins and filament orientation, has an extremely long life, and produces 85 lumens (compared to 25 lumens for the original and 125 lumens for the H6W).
The fog bulbs are indeed nonhalogen units. There are handmade halogen bulbs offered, but they're very slow sellers; most people figure they're not worth the trouble or expense, and they're probably right
--Stern (hope it was OK to put in those links...)