Cyl sidewall wear with a 416

Yes, the 4" arm with the rod ratio of 1.55 will wear a hell of a lot faster than 1.85 which is the 340 rod ratio. I'm not familiar with that shop, but that's not real telling. There's more I dont know than more I do. The things that will affect the wall stability are stroke, rod, piston, wall thickness, wall finish, and cleanliness. The only things we have full control over are the last two, and we can check for the third. If the wall finish is rough, they will wear faster adn wear the pistons faster. I would say pull a couple rods and actually measure the piston and the bore. Short pistons rocka lot at TDC, and .005 is a lot of side clearance. But, if it's all right, the wall clearance tightens up when it's at operating temp. I'll also note ring seal also goes away a lot faster. My life expectancy for them is 25-30K miles before they will need attention. Most vehicles are not driven daily or tremendous distances, so that's not an issue. I have seen one or two go twice that, but a lot depends on the machining and parts used.
Off topic, but this is why I'm not for strokes longer than 3.915 in B wedges.