As most of our cars are put together with used parts (and the OEM shifter parts, like the nylon gearshift lever/ball, are growing increasingly NLA) there's probably a good amount who would be interested in seeing a thread documenting your enhancement to the available parts. I've seen the zip tie approach, but would be interested to see the specs of the o-rings you sourced.But, It did not seem to shorten the side to side up much which seems to be what you are after. That's a function of how the mechanism works (angular motion vs. linear motion). PM me if you want details of what I did. Or, I can start a new thread on it.
As for getting me the lateral movement that I desire, I don't anticipate the short shifter improving things in that aspect beyond a new ball and socket ideally reducing any slop that may be preventing full translation of the movement at the knob to the selector shaft on the transmission. By stabilizer rod adjustment are you talking about the bolt at the front of the shift mechanism that controls fore and aft placement of the shifter? I've played around with that adjustment, but it doesn't seem to have had any influence on my issue.
My comment about notchiness is just a general one on my overall experience with short shifters, nothing specific to the 012 transmission. I just find the increased force and closer engagement points of a short shifter unsatisfying and "notchy" and typically prefer a smoother, albeit longer, shifter throw of OEM.