Follow up; got mast, launched boat, went sailing. Sailing is so much more fun that boat work, beyond compare.
I think that the Hall Spars kit probably looks like the J/24 thru bar, plus they add spreaders. This type of kit is probably best not done by the DIY'er. A simple thru-bar (long bolt??)that utilizes the OEM parts would lend itself more to DIY. The thru bar extends far into the spreader. About 5" & 7" outboard, there are heavy pins thru the spreader and thru bar, about 1" diameter. They are cotter pinned. The rather underbuilt but sufficient OEM spreader is replaced by something that has heavy weld beads, and a completely heavy duty look. It's aluminum, and I did not get a weight of it, it's probably not actually heavy in weight. The shroud goes thru a channel in the outboard end with an end plate (no more bailing wire holding the shrouds).
Since I got the rig on Tuesday & launched it Wednesday, I did not remove the pins to look at the bar because I was busy with launching duties. But you can see that it's a grown up version of the J/24 bar, and clearly one should know exactly how they are going to cut their rig precisely for such a thru bar, prior to cutting. You could go very wrong with that process. Since there are other ways to skin this car, which include a sleeve, or a thru bolt, or several thru bolts, those should be explored among the DIY'ers.
