I know you could drill the holes on the k-member on a '69 to facilitate the positioning of the sway bar attach bracket of the '70, but will the '70 sway bar fit through the middle of the '69 k-member?
No, '70 bar won't fit through the middle of a '68/'69 K. There's no opening in it for the sway bar to pass through.
The '70-style sway bar attach brackets fit on a '69-K through the use of adapter brackets, they won't bolt directly on & line up. You drill holes for the adapter brackets, then bolt the sway bar brackets up to them.
And the 69's only had skid plates on the Hemi.
Really? '69 440 K's didn't have skid plates, either? How about '68 440 K's??
I thought that the 318 or 383 K's did not have the skid plates, but the R/T cars did.