In reply to kevin stephens:
i used to suck hard at big overhangs, in the last 2 years i've almost leveled my performances at them with my slabs and vertical walls. Doing some strenght exercise work helped me a lot, but i wouldn't focus exlusively on your arms/upper body.
if on big overhangs your problems involve :
-losing feet all the time on big moves, and/or having trouble to put them back on the wall
-swinging out of control
-very bad time at managing stretched-out positions
-inability to make good use of poor footholds
-constantly choosing footholds that are high and close to your center of gravity, hard time at seeing how low, far away footholds can be useful
-hips constantly away from the wall, hard time at bringing them closer when required by a move
then train your core first, it is probably a bigger limiting factor than you think, even bigger than your arms.
working on a front lever at the pullup bar is a very good one but needs to be approached carefully and you shouldn't aim directly at it if you are too far, you can harm your lower back.
if you are far, limit yourself to planks : facing down, on the side, reverse.
as far as upper body goes, personally i've felt the most important muscles on overhangs are lats, and you can skip training your biceps in isolation (they will get trained anyway in most lat-specific exercises). Lat machine, rowers, front lever at the pullup bar if you can...