The Rover Co Ltd, LR Workshop manuals were regularly reissued with revisions added right through series production as the model range widened . Each edition is identifiable on the first page. Print dates are to be found.
The latest Series One manual I have Part No 4291 was first printed in March 1960 and my copy is one revised again for reissue in October 1963.
This final 4291 is possibly the most comprehensive of all. But to save space - I suppose - there were some technical operations which appeared in earlier manuals that were omitted, or the operations were simplified with shortened versions put in.
If you have this version, then in my opinion you may already have the most useful one.
Some military manuals issued for REME base unit training etc may be more comprehensive , but copies are very hard to find now.
Manual 4057 also known as TP165B which covers all 86/88/107/109" was first issued in January 1954, then revised in September 1957. It covers many engine operations quite well too, and technical detail does enhances other earlier manuals. This last 1957 edition includes a section at the end on the 2ltr Rover high speed diesel. But other operatons have disappeared or are given are in less detail. I find 4057 less valuable than 4291.
Which number manual do you have at present?