Is this legal? (1971 counterstamped silver dollar)

I bought this interesting coin and my question is, was this action, made on this silver dollar legal, back in 1984? If I take 2000 pieces of a, lets say, 1 dollar coin, year 2001 and counterstamp them with whatever I like and sell them in USA, is my action legal?
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@1984worldcoins Could be a Mel Wacks counter stamped coin. He's done quite a few of them commemorating different events over the years. I have a few of his counter stamped coins (see photo).
Sugar magnolia blossoms blooming, heads all empty and I don't care ...
Yes. It was - and is - legal.
Is that a 40% silver dollar or is it a clad dollar? Mel Wacks does great work and his counter stamped coins are very collectable.
Worry is the interest you pay on a debt you may not owe.
"Paper money eventually returns to its intrinsic value---zero."----Voltaire
"Everything you say should be true, but not everything true should be said."----Voltaire
Aren't most of the Mel Wacks Ikes 40%?
Mel Wacks stamped coins usually command a premium. His stamps commemorate significant events and are very well done. Cheers, RickO