With the cracks glued and cleated as I thought needed, time to fit the new bass bar.
First, layout in pencil. We want the bass bar to be under the foot of the bridge, 'east to west', in a sense as measured from center-line, or from the edge of the f-hole, or some place to hook the tape-measure, as it were. I also don't want it to overlap the upper terminal hole of the f-hole. With these two constraints, there is usually not much choice. We also want it angled relative to the spruce grain, for strength purposes. Lining the bass bar along the grain is a great way to crack the top.
The problem with old tops is that they are not always normal.