Thanks from your reply from down under. Im pleased I didnt have to turn my screen upside down in order to read your text! ;-)
So I take it from your reply that you are unaware of any source for a rear sight elevation slide, rear handguard and stock. Frankly, I doubt Ill ever find these bits, but I can't know unless I ask.

I have already restored the stock and handguard within the limits possible. They are serviceable, and the resulting cosmetics are not terrible, but noticeable, at last to me.
The rear sight elevation slide is, however, far more an issue as this makes the rifle incomplete, despite the fact that few notice...I do, and it offends my German sense of symmetry (small personal family history joke, despite the fact that we moved from Germanyicon to the Colonies in 1737). This rifle was in my 104 long arm collection that was recently on display at a local museum for 2 years, and I was proud that it completed the UKicon arms of WWI section.

Like you, I do not collect pristine museum pieces, but prefer arms that have clearly been in the hands of actual soldiers. I prefer the dings dents and slight wear of an adequately maintained but clearly used rifle. I lack written provenance of each rifle of my collection, so I can never claim the rifles have even actually been used in battle, least of all which theatre of operation or battle itself. However it is likely that each of my rifles have in fact been to battle...if only they could tell their story!

Also like you, I perform the minimum repairs and use established and historical armorer's methods where possible and as needed to the best of my ability. Also like you, I extensively recondition the furniture of every one of these rifles with BLOicon and apply maintenance coats at least once a year, if not more often. I reject the misinformed notion that raw Linseed Oil should be used instead for chemical and practical reasons, as well as historic since the original coats were applied by dipping the furniture in heated Linseed Oil which, due to the elevated temp and oxidation over time, resulted in the same chemistry of the finish as BLOicon does today. Were an authentic used stock and handguard become available I would prefer to improve my rifle with better furniture, but I rarely, if ever, use NOS or repro furniture parts.