Thanks for your collegial comments.
I have not read Orr's analysis, but I will give it a whirl.
Certainly LHO acted like a guilty or framed party in the immediate post-JFKA moments and minutes.
My suspicion is that he was involved in the JFKA, although who can say how, with any degree of certainty?
The HSCA, full of smart and skeptical people, concluded there had been a JFKA conspiracy, but that LHO fired the lethal shots. Maybe so.
I wonder if LHO did a repeat of his Walker evening (IMHO), and fired, but intentionally to miss. That would explain the three missed shots on 11/22 seen by many witnesses (one striking the asphalt behind the limo, one striking the Elm St. adjacent manhole cover, and another near Tague).
I lean towards a second gunsel behind the limo, perhaps, as you say, on the Dal-Tex roof, or elsewhere on TSBD6.
Then the GK smoke-and-bang show, which was possibly a diversion.
As stated, in my view, the JFKA conspiracy was very small, possibly even just Herminio Diaz and Eladio Del Valle. Del Valle was a pol back in Cuba, thus likely somewhat polished, able to speak to LHO, win his confidence.
As for "professional hit man"--well maybe. What the horrible Trump assassination attempt (missed by an inch), and the equally horrible Kirk assassination show is that relative amateurs with rifles are very dangerous. JFK was moving, but nearly in a straight line away from the TSBD/Dal-Rex buildings.
Anyone reasonably familiar with a rifle could have perped the deed. But not a lone gunman with a single-shot bolt-action rifle.
IMHO, caveat emptor, and draw your conclusions.