I've had quite a few 70's era knives and still have some.
IMO in general, they were still good, although usually not up to the same level of quality of the XX era knives...
Maybe I have been lucky but I really haven't had any quality issues with them.
If its priced reasonable and you like it, get it. The 70's era yellow knives don't really seem to come up on the market as often as the other versions