LF DISC BRAKE KIT/HELP 67 DART

That first "kit" that you list, says it's for 10 inch drums, but if you look at their description pictures, it's showing a 9 inch Drum spindle.
Something isn't right with that ad, and or pictures.
Be wary, of that one.

Your car have 9 inch, or 10 inch brakes, on it currently?