The one in my car is OK, but I'm running a new set of wiring through it... just need to be careful with it.
I have NEVER seen one that was bad. They are stiff,but you can tuck some additional wires in them. How many or have big?
Brian, you're likely right that there won't be a problem. At this point in the resto, I've been trained to assume that old plastic parts that get any force applied to them will explode.... I'll be running a new rear wiring set through it, along with speakers and rear defrost.
For the most part those ribbons don't go bad. Just make sure the connections are clean & test with an ohm meter or continuity tester.
Would suspect '70 - '72 Chevelle is the same. The floor stamping should be the same, and the fuse block should be in the same place on the firewall.
It's gonna be a grand, dirty time: removing seats, rugs, sound deadener, mysterious congealed seam sealer goop... then the wiring ribbon. I think I'll have touched every part of this "clean" car once done....