Thanks for the offer but I think I know what I want for a receiver wrench.
The metal part of it is going to be a 1*1.5 or 2" tube 2-3' long with a steel block welded to it that fits in the area under the barrel threads. I'll probably make a matching cheater for it.
The wood is going to be a roughly semicircular piece of oak with a cutout for the exterior of the receiver.
The reason for being semicircular is that I'm going to use a steel band to compress and locate the wood over the steel handle.
That will make close to 100% bearing surface for 1" of the receiver, non-marring and with the barrel mounted sight side up on the left of my bench, the motion to torque the receiver will be downward and the wrench handle will wind up close to horizontal to the right, parallel to the bench top when properly timed so that I can treat the bench top like a handle on the barrel vise, that should be ergonomic.
It might be a little more work than copying CMP style but I think I will have a better wrench. I want the horizontal setup after reading the poor reviews of the Brownells receiver wrench because one customer didn't like the way it points down. I saw a video of the CMP wrench and it was pointing straight up which is better but still not ideal.