I use LED's in my side markers. Gives out a nice white light.
I bought a box of these odd NOS bulbs off of eBay awhile back. I'll let you know the type when I get home around from work and can get you the bulb part number. If you can't find any local, or you can't find any on eBay, let me know and I'll sell you some.
The cornering light bulb is a 50 cp (candle power) 1195 bulb. It is brighter than the typical 32 CP 1157 tail park and light bulb, and32 CP 1156 backup bulbs. I have VG used tested 1195 cornering light bulbs for $1.50 each or new ones like the one you see below for $3 each. I currently have about 20 new ones on hand. If you or anyone wants one email me at email@example.com and include shipping address.
Just to add, the LH cornering light in your picture has a very dull, corroded finish and you can put any kind of light in there and it is only going to be so bright and only throw light so far. To get the original brightness and really throw the light out to the front side as the cornering light was designed you need cornering lamps with nice shiny interior surface. If you just put a light in the cornering light fixture in your picture it will be seen, but will not throw the light out. If you want some thing really nice you might consider something like this LH driver side cornering light and park light assembly I have up for sale:
Excellent 64 LH Cornering/Park Light From 41K Mile Donor Car $135 <-- Click for more pictures