A quick search of the web yields the following data:
1157: 440 lumens (402 H + 38 L, since you are running both filaments at the same time) at 35.7 watts (27.3H + 8.4L) for an efficacy of 12.3 lumens/watt. Chad, keep an eye on the lenses - they might get pretty warm.
1142 LED: 120 lumens at 2.1 watts (12V x 175mA rated current) for efficacy of 57.1 lumens per watt. If the same type of source could be found with all the LEDs facing "forward" this would help effective use of the lumens greatly.
Neat projects, either way.