Well if this coin wasn't the first struck off a pair of retired proof dies, only 39700 minted I'm saying yeah" 63 " MS PL details cleaned. From your images very strong strike using a fresh proof die album toned and dipped and cleaned. But both Liberty and the eagle look frosty.
I'd be in the same camp as @Paddy54 . . . Unc Details - Cleaned, except that is not one of the selectable options. AU58
The details scream AU-58, but the pictures show a lack of luster in the fields. If the fields retain 90%+ of the mint luster, then it is AU-58. If not, then it is AU-55.
I started at 55, but went back and changed to 58 as the high point rub looks so minimal. Lovely coin!
AU58: Rev- There appears to be wear on the tip of the wing just above the "T" in TWENTY. There may also be very light rub on the eagle's chest feathers. Obv. I don't really see any wear from the photos. Looks proof-like, as well.
I think I can share this without really revealing anything... this is a crazy coin. I don’t have the resolution to be able to show it on a coin this small, but it is completely covered in die polish on both sides. I was thinking the same thing as you with the proof dies Paddy, the frosty devices are there too. It has a thick skin and full luster under a light source, but definitely a tough coin to try and assign a grade to. I’m enjoying hypothesizing, any twenty cent specialists around here?
They did reuse proof does for the 75-P. In fact, it's not uncommon to find PL examples. I posted on a while back. Lemme see if I can find it.
AU dip. Still a beauty. Love the double dimes. Yes the image on both sides are startling for this series. But I believe this coin circulated lightly. (Not that the grading boobs won't give it an MS.)