I've built wheels with that OLD on my older Park TS2 and had no concern about the angle of the arms - just didn't think about it. I also was not concerned that the faces of the arms were or were not square with the faces of the lock nuts. This will seldom be the case, but it really doesn't matter as long as the hub is held in a stable position. I never rely on the alignment of the Park stand to assure a proper dish and so, in every case, I use a dishing tool. I'd recommend continuing with your current truing stand and buy a cheap dish gauge (or fabricate a DIY solution). Save your money for a spoke tension gauge.
Good luck on your project.