I would say MS63. Might get a 64 for the toning...but I going to say MS63 based on the hits on the obverse.
It is a technical 63 for sure. Only question is does it get a color bump? I think probably, even though the fade to black rainbows are terminal toning.
Nice looking Morgan! I'd call it a 63 myself. Typically color bumps don't happen unless the toning is on the obverse, with the exception for outstanding color. The reverse is a solid 64 the obverse is a weak 63 in my opinion, which is the more important side.
I am with some others. Color on reverse too terminal and in danger of quickly corroding the coin if not already. 63 I thought was a little generous given nearly all marks on the obverse are in the prime focal areas.