My problem with this is that I DID build and fly in those times (late 60s, early 70s) and ALL of my pattern models, Super Kaos, Dirty Dirdy, Intruder, Cutlass, Compensator, and later Curare, Tipo, Hippo, and Atlanta all had retracts.
Yes they had retracts in the 60's, late 60's anyway. But they were not common, and models were usually not designed for them, so most were an afterthought. However, I don't see any 60's design in your list? Some are early 70's, the Super Kaos for example was a redesign of the Kaos, specifically to add retracts. I believe the Kaos was published in 1970 and the Super Kaos in 72 or 73. The Intruder came out in 72 or 73. ....not sure about the Compensator.