If you look in Waller, he mentions the danger of damage to the flange around the magneto drive hole on a 4G and says it can and should be built up with weld. An easier solution is to fit an insert, particularly if the damage is severe. I think what you have is a selection of solutions to the problem. The best answer is an aluminium insert but centring it accurately may be a problem. Steel inserts will tend to come loose due to the greater expansion of aluminium when heated - and the Square Four gets hot !
36 4G, 37 VH, 53 ex ISDT KHA (project), 54 KH(A), 54 4G Mk IV (project), Healey 1000/4 (project)
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser.