Practically all countries which still had in 1960s silver coins in circulation stopped issuing silver into circulation in 1968-1969. Older silver coins often remained in circulation until most were picked out and kept by the public, but no silver coin was mint for circulation since 1969 (not to mix with "legal tender"). Therefore the answer to your question is "no".
I collect coins and tokens which circulated in Africa from 18th century to 2000. I sell about 7000 illustrated world coins from http://www.avscoins.com.
Guess these were available at face value and legal tender. It's slightly less than a troy ounce of silver which was worth a few dollars back then. Not entirely sure about the USD/FRF exchange rate in 1975 but likely to have been close to 6. With a face value of 8 USD the silver was worth less.
Of course by 1980 the silver was worth more than 40 USD, until Silver Tuesday ruined the ambitions of the Hunt brothers who literally lost their shirts on a bet silver would return as monetary base.
