Hi. How hard is that darker stuff on the reverse
, hard would make this a tough one to do unless you've done other similar ones!
What you take off could mean no patina
under, or something even less attractive. The small poc marks look like they are within the substance, not on top of it.
I would agree with awl, in that its worth considering the price
and scarcity of coin like this, lest you make a mistake you will regret (been there, greater than once).