Jack-
In 1973, I wandered into Bart's Sports World and was dazzled by the wall of bows - almost as many as you have now. I bought my first bow, a red striped super grizzly with the Victor decal and raised button. I had been taught the step through method of stringing, and strung and unstrung it every time I used it.
I did this for ten years until someone showed me a bowstringer.
The old grizz has no stress lines 35 years later, and despite my best efforts, no twisted limbs.
That being said, I now have picked up super Ks, kodiak hunters, grizzlys, tigercats, black bears, tamerlanes, and other bows from the 60s and 70s.
The quality may have gone down, but the futurewood bows I collected have no stress lines or twist.
I think that old Fred hired the right people, and learned a lot about mixing epoxy and limb design from the lessons learned in the 50s and 60s.
What I think matters most is:
Was the used bow dry fired?
Was it stored in a hot attic, or standing on one end in a closet?
Did the past owners put fast flite strings on it and shoot light arrows?