The more level the better as the drag link goes but don't lose sleep over it. Some bump steer is only annoying, lots of bump steer is dangerous. My take on the bent drag links is they need to be made illegal. An extreme angle between the two ends is always going to be an extreme angle even with a bent bar between them. Bring one end up and the other is stationary (simply put) and the distance between the ends changes, with a bent bar you get the same bump steer as you would if you used a straight bar between them. Solid is solid.
As far as not getting full lock to lock steering...that could be many things. Jack the front up and swing the tires while watching everything, see what may may be interfering. Then look at the bottom of the steering knuckles on the rearward side, there you MIGHT find a couple of bolts screwed into the axle housing and acting as stops for the steering arc. Doubtful but you might get lucky. Mine had them and making the turning radius slightly sharper was easy; but that's another thread.
If you followed Viles instructions on setting the steering box to center there shouldn't be any steering related reason why they won't turn lock to lock. Maybe hitting the oil pan? Toe set seriously poorly? The steering on a K truck is certainly not complicated. Steering wheel, steering column with associated parts, steering box, pitman arm, drag link, steering arm, 2 knuckles and a connecting rod. Not really much to it.