I got a little bumpsteer on my 94 when I converted from a trackbar in the stock location to an OAB with a build-it trackbar (ORGS MFG, now JKS.) The steering was not touched, it's a Heim conversion to a crossover. After the conversion, the trackbar and the draglink are almost perfectly parallel, but the trackbar is significantly shorter. When the suspension cycles, I do get some steering effect.
I will agree that having the trackbar and the draglink parallel is important, the length also affects steering. The ideal situation is angle and length are both identical. And if you have to make a choice, make the angle the same, it'll affect steering less than length, especially if you can get them as flat as possible.