[unruhjonny]

Just to be clear, if 301 is to be interpreted as 30th week of 1971, then that would put it as being made the week of July 11th 1971;
Again, between the 11th and 17th of July.

If your car was sold in March 1971, then that tire is too new to be the original tire.

I would suggest that the tire in question is NOT the original tire that was sold with that car.

When did Europe adapt to metric tires sizes?
Or maybe more specifically, when did Switzerland?

In North America, metric tire sizes only started showing up in the 1980's - and till they became the standard, the older style letter series tires were being sold.

If you do not have conclusive evidence, I'd say that "1" indicates 1981.

I just did a search, and it reads as though Switzerland only went fully metric by joining the international system of units in 1977... But I will assume you to be the governing body in this conversation as to when metric sized tires were being sold in Switzerland.
Canada started going metric in 1973;
I actually have a spare set of 1970 Firebird gauges with a really old KPH overlay on the speedometer.
While the first year of dual (MPH & KPH) speedometers was 1975, the first year that Canadian cars came with KPH as predominant was 1979.

EDIT: Additionally, unless I am mistaken, the 205 section width would be too small for an original tire for your car.
I believe that a G70-14 (OEM as built) would cross to a 225 70 R14;
Is the "V" just an older indicator of the ratio and radial "R" in indicator of it being a radial tire...