There's no pit at the Lexington so just get to the front early and stay there. You can get within touching distance of the stage.
Generally for gigs a wide and shortish tele would suffice (think 24mm and 85mm on full frame). So your wide zoom and 50mm on a crop is in the correct ballpark. Even though I often use a 180mm for head and shoulders portraits, that's an optional luxury - I agree the 70-200 is overkill for a pub gig. Keep shutter speed 1/160th or over to freeze motion. That probably won't be possible with the zoom so just do the best you can. Shoot raw+JPG so you've got some instant results from the JPG but can process the raws properly later. Use earplugs. Get your settings right at the start and don't be tempted to chimp too much - you could miss a priceless moment on stage. Try and get it all in the bag in the first three or four songs - the audience don't want a photographer snapping away through the whole gig, and you deserve to listen to the music too. Have fun!
