We understand your feelings about having Ruger do the safety transfer bar conversion. Here's a few thoughts.
Remove the OM parts, ship to Ruger, let them re-blue it to their standards. When it returns, re-convert it to it's original configuration. When they do the conversion, they only mark the frame, in-between the grip frame & main frame. It's not externally visible, nor does it detract from the value to a collector.
(Reblueing will detract from the value.)
You can also try "Tyler Gun Works" in Texas. They do a superb job of Ruger work.