I definitely wouldn’t worry about it too much. I mean, if you knew your car had one and just needed to make it correct I guess. But like I said not even all the 340 cars had them. They were supposed to, but we know how that worked with Ma Mopar.
I think reinforcing the k-frame is important, especially at the LCA pivots. But you can easily do a better job than what the factory did with just some HD washers at the same location.