That sort of thing can turn into a bit of a can of worms.
You take Guided By Voices...
While they do go all the way back to around the same time as the bands mentioned?
The latest version of the band only has a little bit in common with the band from that time.
Does that take the band off of the board if you are attempting to come up with a "Great Classic Rock..." band?
Personally, I tend to think that some of what they have done would put them squarely in that category if you don't lump them into the time that the initial band started in.