As you have a 6D and 5D I'd go without any strobes etc. A static subject shouldn't pose too much problem but you will have to shoot a lot of frames to pick the one with the minimum of blinkers.
5 frames a second for about 5 seconds should get you a frame with minimum blinkers and without the hassle of strobes. Strobes make folks blink and 70 peeps in the frame is going to be a nightmare without a lot of experience.
Cleaning up noise is going to be easier than dealing with strobe shadows. Shoot cleanley exposing to the right if you're a raw shooter .
As long as you are happy with dark eye sockets that would be an option.