Front end wont stay aligned

Not sure what to say about all that, except LCA and strut rod bushings but you said everything is new.
When everything looks right and then suddenly changes something is moving and it's as simple as that.

Pins through the K like you mentioned is also common enough to check them to be sure, and take a good look at the steering box area for loose bolts or cracking around it.

Also, you do consider ball joints as being in the everything new category, right?:D

Yes lol. I actually put another set of brand new lower ball joints on with no success. I put new ones on my 65 coronet one time and 2 months later I had to replace the passenger side.