Kenneth
I haven’t seen any recent entries in the thread so perhaps you have not gotten farther on your project.
White LEDs are more efficient in generating photo-useful light than tungsten bulbs and about as efficient as HIDs. They are better tban HIDs in that they are very rugged, can be turned on and off with no warmup or cooldown delays and have 10s of thousands hour life.
Having said all that- you can’t get something for nothing. To get a lot of light you will need a lot of power. You can use as a comparison the power and light output of HIDs.
You’re right in thinking of a lot of LEDs since LEDs give less light if they get hot because of increased power; less power per LED is generally better to achieve the high efficiency specs put out by the LED manufacturers.
Finally- since the light power and input power will be constant, it will be “wasted” when the shutter is closed. That is why strobes are the preferred light source for still cameras!
Good luck.
Divetechx