I reckon the work has been very nicely done too, but has to be said there's precious little casting left on the inside sides from what I can see. A millimetre or so, assuming the tops on show represent the true major diameter of the parts? Maybe his barrels flew off some time in the distant past, ref other war stories hereabouts, and that's why he had to make the stepped bits so wide.
I'm far from against these quali-bodges - I have often had to resort to similar to get round problems quickly, effectively and at nil cost. But I think I'd have hesitated here, given the lack of meat and that it's soft. Not sure what the engineering rules are concerning the minimum amount of material to be left outboard of a threaded hole of given size in any given material, but there'll be some for sure. This has to be close. Still, he seems to have got away with it. Hope it holds together with RGS style horses leaping around. Suggest Forth (or should I say Sydney Harbour) Bridge parts for the head steady!
