... I wonder if the cutoff setting has much effect on rod bushing wear...
Yes, it does.
If the cutoff is set too short, the machinery will grumble about it because there is not enough steam left in the cylinder at the end of the stroke for proper compression. This "compression" occurs at the end of the stroke when the piston reverses direction. If the proper amount of steam is left in the cylinder when the exhaust port closes, it is compressed at the end of the stroke and "eases" the piston to a stop and starts it moving in the opposite direction.
If the cutoff is too short, there is little or no steam left in the cylinder when the exhaust port closes. Without that steam in the cylinder, there is nothing to compress at the end of the stroke to ease the piston's change of direction. The result is the machinery makes noise - a little clanking and banging in step with the rotation of the wheels. Each clank and bang takes a tiny bit of life out of the bushing.
Yes, the 765 was totally quiet when we first put her back on the road in 2006 after the overhaul. She is making a little rod noise now, but she's entitled. Those rod brasses have somewhere around 40,000 miles on them now! But the tiny bit of rod noise she makes now is nothing compared to what she sounded like in 1993 when everything in the running gear was completely worn out. I'm sure somebody will find a clip on YouTube. 
