One thing that stands out to me is the two different backing plates on Alan,s and TB,s AJ Parker sight and TB,s looks like there is a faint outline where another one may of been?
On a Engineering point of view, if I was to go to the trouble of using an end mill to remove previous marks etc I would choose the correct one so to remove the marks with one pass, the photo shows it has had two passes with a cutter due to the incorrect size of mill being used.
That tells me that only one size of mill was available at the time, and I very much doubt Enfield had only one end mill ? I would of thought they would of removed the previous marks with one straight pass, with an end mill or a horizontal miller, or grinder.
Superbee mentions a price 18 years ago, I would feel a lot safer or not as suspicious as I would now buying something like an Enforcer, due to the fact not many of us had a PC back then so the information required for the not so honest was not available.