Sent away a few older coins to PCGS to get re-holdered and imaged. First of the bunch happens to be one of my favorite designs ever. I'm generally not a huge fan of toned coins and prefer "white" specimens where possible, but back in the day, I simply couldn't pass up this beauty.
it's hard with all the toning but a couple of areas look to have slight wear so I am going with AU-58
I kind of agree with the above poster, it looks like it could be a slider....but I'll guess it got an MS64 grade.
As always, several of you nailed it - the coin is in fact MS64. I currently only own this one, but am hoping to some day complete a full set of these.