OP, your rifle is converted, but you do not say by whom. As per the previous posts, if I was in the market for a former DCRA / CAL conversion to 7.62, the markings on receiver, on the bolt and on the bolt head would get my attention first. Serial numbers, not so much. Next concern to me would be the condition of the rails at that bolt head removal slot. It is a Long Branch. That means it is a Mk.1*, as your pictures show. That means it has that weakness / wear point / failure point that did not exist on the Mk.1 rifles. All would be reflected in the price, to a knowledgeable buyer. If buyer does not know or care, the value could be anything?
My Lee Enfield reference book is not here yet, but going from "memory" - I think the Sterling mag might have been more appropriate in the L39/L42 type of rifles??? I think there was an Enfield made magazine as well, for that 7.62 application? I will have to go with previous posters that the Sterling magazine was not part of the DCRA conversion - I have no references that say one way or another about that, but at least as for your opening post, you are not claiming the rifle was a DCRA / CAL conversion.