This won't answer your question about the op-rod but, you can install an adjustable gas plug. The plug will allow you to use factory loads, without worry of bending the op-rod, or a wider variety of handloaded bullet wts. Brownells has them, Shuster and/or McCann "Adjustable Gas System".
I have the Shuster installed and use my M1 for moose hunting. The Shuster uses a set screw and the McCann uses interchangeable screws for adjustment.