I just went through this step on my 14A project. I am by no means an expert with this, and looks like you have some much more experienced advice, but is 1/8" offset between the two counterbalance arms something that needs to be fixed? If you split the difference, thats 1/16'' offset between the two counterbalance arms (unclamped from "trail" position). One counterbalance would be up 1/16" and the other down 1/16" when rigged with elevator pushrod later on...,or checked with wood block between horns and bolted together and checked now.
Like someone else posted, how does the symmetry of the rest of the L/R elevators look when using the 1/16" offset. Not only trailing edge, but the whole surfaces of the two elevators. Tough to get exact here, but look at them visually and use levels, straight edge, or laser as appropriate to get an idea of what they look like.
The reason I mention this is because when I clamped my counterbalance arms in the trail position, I discovered what appeared (visually, straight edge, laser, etc.) to be an offset between the two elevator surfaces/trailing edges. I ended up, after much consideration, purposely offsetting the counterbalance arms to get better symmetry between the two elevators over all. I then drilled the elevator pushrod bolt hole in the horns. It now "appears" that my overall elevator symmetry is much better and the offset at the counterbalance arms is barely noticeable.
My "fix" appears to be in the minority with the other advice you are getting, but thought I'd put it out for discussion.