I have researched the 64 sms penny for a while now and I do know that there is a very small chance of ever finding one of these in circulation. However, it has been done! Check out the edges of the coin and also just how well struck it is compared to a regular 64 penny. What do you think?
Do you have the references from ones that were found in circulation? Everything I read indicates these came from the mint directors estate, then were sold through Lester Merkin.
I found numerous business strikes in circulation, a few better than yours. The Mint produced 2,648,575,000 of them. Welcome to CT.