The only problem with rotating the hinge pin is that it does not compensate for hook wear or out-of-roundness. You will get some/most return to face, but not like new (it is very unlikely that the hook has no wear or out-of-round). A new, oversize hinge pin is a better approach. If you have M8-1 1/4 threads on the pin, it should be a possibility on metric lathes.

Cockerill was the steel supplier, not a gun making firm.

Good work. Nice to see applied mechanics in action.