I do have a soft spot for MGB`s... (-: As Dave suggested "new" ignition parts can be cheap copies and rubbish..I admit to liking the Luminition electronic set up as a replacement though that would be perhaps 30 years ago.. it looks like your fuel seems clean so hopefully no rust in the tank. Not related to your issue, but I guess to have the ign timing set correctly you require to know what cam is fitted, and of course whatever timing might be printed best check it is OK with whatever fuel you might use.
Good luck in resolving your issue..
