[Crex]

Just from the pics and it's general profile, plus the stepped base, my first guess would be Peter-Wright. Lot of variables to consider, but you are not going to "devalue" by taking a wire brush to it. These days old anvils in that good a condition bring a bit more than "antique/heirloom" prices. Only thing most buyer's are concerned about are the rebound, deck condition, and any possible cracks and or de-lamination.

Once you've wired it a bit rub a little talcum powder across the surface, most inscriptions will show up no matter how thin or worn.

If not a PW, give a shout our to the ABANA group, plenty of experts over there.