I have nothing of value to add to this thread, because I don't know squat about why there are so few aftermarket parts for Winchester 70s, nor Winchester or Remington's manufacturing woes, let alone those from the 60's.
I do however, like posting pictures of my great grandfather's Model 70 in .270 Win from 1937. I don't shoot it much anymore, but probably should. I believe this pic was taken the last time I pulled the trigger on it, in 2016, maybe earlier.