I run a parallel 4 link with a track bar in my Model A. The track bar is mounted to the left lower fwd 4 bar mount on the chassis and traverses over to the right lower aft 4 bar mount on the rearend housing. With this type setup there shouldn't be any lateral (side to side, left to right) movement of the rearend in relation to the chassis. The position of the lower 4 bars to track bar, makes 2 triangles that are parallel to each other. One is supported through the rearend housing, the other through the chassis itself. Since all the 4 bar mounts are fixed and parallel to each other, there should be no lateral travel between the chassis and rearend even while the rearend is moving up and down through is arc. I don't believe there is any loading and unloading work through the rearend as stated earlier. I can remove the my coilovers and move the rearend up and down to the extremes with no binding/loading at all. If there was any lateral movement, it would have to come from the 4 bar mounting plates that are welded to the chassis, flexing. Possible but not likely. In my opinion this is a better setup vs. a panhard bar. The only drawback is space, and while doing gear changes.
I have encountered the death wobble twice. The main reason for me was I was trying to run the lightest coilover spring rate possible, and run the least amount of rebound possible. The fix was either more spring rate or in my case I dialed in more rebound. Problem solved.
As far as Triangulated vs. Parallel, the OEM's have used the triangulated for eons for a reason, they are fairly easy to install with the space constraints considered. No panhard bar or track bar to deal with. It's built into the geometry of the triangulated mounting system. In a hot rod I don't think you can go wrong either way.
I chose parallel 4 link with a track bar because it fit the build of the car!

Keith