This looks like a Scott #65, since I don't see a grill - but just a quick look reveals that it is heavily toned and has shifted the color toward the yellow-orange spectrum. I would suggest a careful soaking to see if any of that can be improved without damaging.
This stamp is notorious for changelings and subtle differences in the original ink used which makes it a tough one. I sent a few in to Bill Weiss back in the day and I hit the jackpot (unfortuneatly, due to condition there wasn't much in the pot, but anyhow...)
He sent them all back with a helpful post-it attached:

The upper-left one turned out to be a #64!


Hope that helps a little,
Al
(edited for typo)