I think that it will almost be a must if you want to shoot it very fast.I'm going to use a "fish gill" style compensator - think Barrett .50 - that pulls the gun away from your shoulder to help minimize recoil.
that .50-110 cant have much for a pin even if it were raised.
I am sitting here with a 458 win mag barrel and my trusty Yugo trunion paper weight. It has a slightly larger chamber than the 45-70 I can assure you the pin will not enter the chamber if left as is. how thin can one go in that area I dont know. But think about this, on a chineese barrel with a 19mm trunion the pin groove gets pretty close to the chamber as well! this handel about the same pressures as you 45-70. You may be able to use it as is.