I believe the light I have will take incandescent as well, though I thought LED might be safer with the straw.
I can’t imagine why you would want to use an incandescent bulb for lighting these days. LED gives all the light you can want for a fraction of the electricity. An incandescent bulb gives off the rest as heat. (I actually found a 60 W incandescent, mounted low, is plenty warm for brooding a small number of chicks, and I am squirreling away my remaining ones for this purpose as I replace them with LEDs.)
If your fixture says it takes 75W, that’s an old label aimed at incandescent bulbs. You could easily and safely use 100W-equivalent LED in the fixture - it should be less than 20 W - or one of the smaller screw-in garage lights if it will fit (i.e. the cage is removable).
I use 2 LED under-cabinet lights on the ceiling of my coop which is only 6‘ tall, 3’ wide by 11.5’ long. The lights’ low profile means they are out of the way of my head, and the long narrow shape (they are mounted end to end) gives even light along the coop. They each have a high and low setting, 5.5W and 11W. I have one on the low setting plugged into a timer, coming on in the morning to wake them up so I got winter eggs, but if I want good light in there, even after dark, I turn both on high and have no complaints. They just plug in, are not hardwired, so I lead their cord out of the coop (which is in my barn) to a convenient outlet. Hardwired is optimal but this looks perfectly safe to me (and unlike hardwired fixtures allows easy use of the timer).
Edit: oops, didn’t see that this thread is a couple weeks old – I thought I got here from the “new posts” list but apparently it was linked at the bottom of another thread I was reading. Oh well, at least it’s not years old!