Pretty sure the earth wire is supposed to go to the trem spring mounts in these. I haven't built this specific kit so not entirely sure - but on the strats and JMAs the earth is soldered to the spring claw. If what you have done works then don't worry about - there is zero danger of shock.

And yes seems like back bow in the neck, a piece of flat aluminium bar (about $8 at the big green shed) and an angle grinder and you can knock up a notched straight edge in about 10 minutes. Like this






Very handy for truss rod adjustments.