For me, it evokes nostalgia:  Peter Max and Yellow Submarine and all that.  But I don't think Jack would have gone for the hippy-trippy feel.

I'm biased toward Tom Kidd's approaches to Vance illustration, but the one piece that has always stuck in my mind was Jack Gaughan's cover illo for the edition of Galaxy magazine that featured The Dragon Masters.  More than fifty years now, and I still remember the energy of it.  And given the state of my memory, that's saying something.

https://upload.wikimedia.org/wikipedia/commons/d/d0/Galaxy_196208.jpg