I am very electrickity challenged but I thought a 14.4v bulb could handle that many volts, 12v should still light it fine? No idea how 100 mA relates to watts and all that.
Read the thread on LED conversion too, cool.
My situation is a bit unique in that my dash is 1" thick oak so the fuel and oil/temp gauges (that normally just get incidental light through their little blue windows from a bulb shining on the back of the dash) were not lighted at all.
Since I wanted to install a pointless ignition which led to converting to negative earth, which led to an engine bay clean up, which led to a full harness replacement which led to pulling the dash which led to re-doing the whole dash....I cut tunnels in the wood around the perimeter of these two gauges and am mounting the old harness's high beam warning and ignition warning lamps to shine into these tunnels. Works great but leaves me a couple bulbs short.