Any idea of the venue conditions? I’m assuming evening, dark, stage lighting?
What type of concert? An orchestra is a different beast than a rock show…
Is there a photo pit at the venue? Sometimes you’ll get access right up to the stage pit area (and usually they’ll only let you shoot for a few songs at most). Try to not shoot into LED lights (or lasers!) if possible.
I’d opt for the speed as much as possible (even at the cost of noise - don’t be afraid to bump the ISO if you need to - better a grainy shot you can see than a blurry one with less noise). I also imagine that to stay fast you’ll likely want to choose fixed focal length, something short maybe? If so - you’re going to need to be spry on your feet…
I’d keep that aperture cranked as wide open as you can and leave it there (unless you’re able to get over 1⁄500 or so.
Probably try to keep the shutter speed above 1⁄120 or so. Something fast enough to freeze the motion in your scene reasonably well.
Adjust ISO to let you sit in those two ranges above as needed. Rent or borrow faster glass if you need to.