Goodyear Polyglass E70-14 needed
I would hate to risk my car if I ever needed to use a 40 year old spare. (Note: I have my 40 year old tire in my trunk so I don't follow my own advise)
Did you go with Polyglass E70-14s on the rest of the car? Never did see what you decided....
If you went with the BFG Radials you would be better off with a radial in the trunk... 3 radials and 1 bias ply could make the car drive strange if you had to put that spare on the road.
If you want an original in the trunk, pay the 200 at least then you will know the tire won't explode when you need it.