One of your links is of the Dodge color chart and the other link is to the Plymouth color chart. Dodge and Plymouth called their colors different names BUT the colors were accually the same. A5 is the paint color. The letter infront(J in this case) is the year that the color was first available.
F= 1970
G=1971
H=1972
J=1973....they skipped I because it looks like a 1(just guessing)
You can go to any automotive paint supply store and they can mix you the correct paint. Just tell them A5 and they can mix that color. Since you want to touch up your existing paint, you'll want them to color match what you already have. They should be able to do that no problem.
I had a local store mix me up some touch-up paint as well as some body color in a spray can. The color is a perfect match. The only difference is that the spray can paint has a heavier metal flake in it. I've used it on the underside of the car so you can't see the differance in the matal flake.