{4th, 6th & 7th} seems correct.
The 4th issue (Diasqr mold) was released in 1961.
The 6th issue (LgKey mold) was released in 1972.
And the 7th issue (Horseshoe mold) was released in 1985.
Above dates are from the most current "Chip Rack".
So it seems that James' order of issues was correct.
I probably should be posting these "Sets" using just their dates of issue instead,
but old habits sometimes die hard.