Quote: If it were struck on a dime planchet, I would expect the permitter devices to be much closer to the edge
That's what confused me for awhile too - but it wasn't struck on a "Dime planchet" - the blanks it was struck on were punched out of "Dime thickness stock". Allegedly.
Remember, the dime stock blanks were punched out in 1970 and fed into the minting machines. Your coin was minted 5 years before that happened so chances are slim.
Any discrepancy most likely has to be from the worn die problem. Don't know what's going on with the rim if that "line" around it is shadows from the picture or what.