Hi Dee Bee,
I've rotated your photo for you so that our members don't have to do a hand stand to view it.
I think you've got it all covered as far as blasting is concerned. I'm not sure what's been done with a welder on the top section of the lower handlebar assembly ? Maybe you could skilfully grind it back nicely, but it's going to be behind the shield and not really seen. I know what I'd be doing but it's your call.
As far as that snapped off set screw that was used to attach those bogus catcher rubbers I would just nicely cut the lower protruding section of with a small hacksaw and then nicely file it back flush. You are correct in saying that all you have to do is get the early style square block rubbers and push them on the original stubs.
It's interesting that the stubs were still being used at the time your mower was made (as it's an Eagle Farm made machine) and thus it supplies us with evidence that the bolt on rubbers came along when the name Rover appeared on the Kermit green powder coated machines.
Plenty more photo's, we just love more photos !
Cheers,
BB.