A lifting method for  ball valves where one or more plugs are inserted in the flange holes and on the other side a lifting eye is screwed into the plug. Familiar with this kind of lifting ?
As sketched, it's impractical because the plug has to be inserted through the mating flange, which has to be removed to clear the plug's shoulder.
It would be more practical to make the plug without a shoulder, in two pieces, split diagonally like a bicycle handlebar bracket, so it could be inserted from the 'near' side entirely, and expanded by tightening the lifting eye.
Doesn't matter, really; I haven't seen either design offered for sale.  But your machinist would have no difficulty taking it from here.

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