Bill, I changed all mine to LED's. I had difficulty finding LED's for the stock sockets. I changed to wedge sockets. I think I got the sockets here:
http://www.britishwiring.com/Bulbs-Bulb ... =50&page=1I got the wedge bulbs locally in two sizes for the major and minor instruments.
I had installed a lamp brightness control from a Suzuki (I think) when I re-wired the car. It actually works correctly to dim the LED's; not sure if the Plus 2 stock pot will work or not.
I really like the readability of the LED's; huge improvement over stock. The light is a bit more severe in colour tone than the incandescents though, so might not be for everyone.
I can't remember details, but when I was looking at light upgrades, I found halogen instrument bulbs at the Little British Car Company.
http://www.lbcarco.com/Stu