Been installing the tie plates from which to hang the rails. This particular one has been modified to install adjacent to the flue for the wood stove currently in the building. That thing's going to leave as I need the floor space. I'll hang a heat pump from the ceiling or something.

5 of 15 trusses at the rear were outside the 1" of height adjustment I built into the tie plates, so I had to have a second run of plates with longer "necks" made to install at those locations. The situation was similar at the front, but for only 3 of 15 trusses. The second run has been cut and I will get them cleaned and painted this weekend. With both wires set up and all the parts produced, I just need to put in the hours setting up and screwing in the tie plates. I'll also need to reinstall the drywall patches I cut out to keep attic air out of the shop volume. That will pretty much have to happen before we install the rails, but should only be a couple of hours of work.
Brought up my dad's friend's builder's level today. It's a Dewalt sight level using a three point adjustable base with a swiveling telescope that has a level vial attached. So as you set it up, you swing the telescope over each adjustment screw and adjust the vial level. This should fairly quickly level the base and then you get to work.
However, it didn't. I checked by swinging the scope 180 and the vial didn't read the same as it did the other way... Sigh. My definition of level is apparently better than that of the guy who calibrated the instrument... who probably worked in the Dewalt factory on the day the gizmo was built.
I compensated for the calibration error and was able to dial it in quickly after I knew about the problem.
The rear wire was 1/8" out of level over 30 feet... not bad for using a 6' level and some plastic shims to measure the relative elevation of crooked-ass trusses.
My dad and I had been debating the level state of the front wire. I thought the south end was 1/4" low based on the data from the trusses, but to arrive at that conclusion, I had to throw out three measurements (out of 15) that weren't matching up. He was using these measurements to come to the conclusion that it was fine as it was.
The sight level said I was right
We adjusted the wire at the front of the building level, but did find that it's 11/16" higher than the wire at the rear of the building. That's not a huge deal, as I can compensate for that in the end fixture plates that will attach the bridge to the rail trolleys.
The "rails" are usually called the "runway"... but since mine's not built into the building structure, I have a hard time calling it a runway.