The guns were returned from conversion equipped with:
1-303 extractor (works fine as a single shot)
1-303 magazine (used as a single loading platform)
1-303 Cmk4 rear sight (competitors (usually) replaced with their own sights)
About 50% of the DCRA 7.62 conversions I have seen are on
British commercial proof marked actions...be they Long Branch, Savage, Maltby, BSA or Fazakerley.
Actions used were: No4MkI, No4MkI*, No4MkI/3, No4MkI/2 and No4Mk2 (I have owned examples of each).
I've seen (and owned) a number of rifles
butchered to install Sterling (type and style) ejectors...The Indian (2A1) and Enfield (L8/L42) solutions are much more elegant...
I would fit the extractor to force the case against the side wall of the receiver which will perform most of the function of the ejector.
Since the Numrich Indian 2A1 replacement magazines became available...its much easier to source an inexpensive but excellent quality magazine...which doesn't require machining of the receiver to seat properly. I would modify your magazine to the L8/L42 style by welding an ejector tab to the magazine rather than making any mods to the receiver.
The conversion numbers are on the right side of the receiver ring (often hidden under the wood line), the right side of the barrel reinforce, and the top of the bolt arm as described.
Each conversion number has the technical services "rolled maple leaf/stylized crowfoot/arrow head" with a small "P" at the tip of the point.