Mr.Mark, thanks for your anvil and hammer data. 
All anvil & hammer considerations I have read recommend for good forging efficiency that the anvil mass is as large as possible with respect the mass of the hammer. It is surely fulfilled for ratio 50:1, but already ratio 10:1 is sufficient to be above the knee of the efficiency dependence.
What is not well described in the efficiency considerations is the anvil placement. In my understanding an anvil mounted on a wooden log buried into the ground behaviours like a buoy on a dense viscous liquid. Under the hammer blow it penetrates slightly into the ground, changing its kinetic energy into work necessary to overcome the side friction from the ground. After reaching the maximum depth it elastically rebounds to the initial height above the ground.
In my thinking the mass of the anvil's base increases the effective mass of the anvil which makes the above mentioned ratios very conservative.
So, your anvil/hammer mass ratio guarantees efficient forging, provided that the blade is sufficiently hot. If the blade is not sufficiently hot the hammer rebound is high and the forging efficiency drops no matter how massive the anvil is.
All anvil & hammer considerations I have read recommend for good forging efficiency that the anvil mass is as large as possible with respect the mass of the hammer. It is surely fulfilled for ratio 50:1, but already ratio 10:1 is sufficient to be above the knee of the efficiency dependence.
What is not well described in the efficiency considerations is the anvil placement. In my understanding an anvil mounted on a wooden log buried into the ground behaviours like a buoy on a dense viscous liquid. Under the hammer blow it penetrates slightly into the ground, changing its kinetic energy into work necessary to overcome the side friction from the ground. After reaching the maximum depth it elastically rebounds to the initial height above the ground.
In my thinking the mass of the anvil's base increases the effective mass of the anvil which makes the above mentioned ratios very conservative.
So, your anvil/hammer mass ratio guarantees efficient forging, provided that the blade is sufficiently hot. If the blade is not sufficiently hot the hammer rebound is high and the forging efficiency drops no matter how massive the anvil is.