Hi everyone,
I have been dreaming about owning a Heuer Bundeswehr 1550 SG for years. Every time I get close to pulling the trigger, doubts creep in. I am hoping this community can help me finally make sense of things.
I am currently evaluating two examples on Chrono24 and I have serious questions about both.

Watch #1 — Full set with Heuer orange box, military black box, Anlagenblatt AAN document with matching NATO number 6645-12-146-3774, 3H red dial, 4-digit serial (3997), 1969, unpolished case.
The seller (based near Frankfurt) states the documents are copies made by the Bundeswehr themselves during the 1970s-80s when the watches were in active Luftwaffe service. The paper looks remarkably white and clean compared to the heavily aged box and strap. Is this a known and documented practice within the Bundeswehr? Do these copies carry any real collector value or are they essentially worthless compared to originals?

Watch #2 — Presented with a Luftwaffe officer's navigation pouch (pencils, rulers, navigation tools), Technisches Handbuch dated 2 MAI 1972, and described as purchased directly from the Luftwaffe officer himself.
The caseback in some watches shows only "BUND" — not "BUNDESWEHR" — above the NATO number. The surface appears bright and mirror-like with what seem to be concentric turning marks (the right one) rather than honest age-related wear. The seller (French) admitted he does not know whether the documents are original or reprints. The story of buying directly from an officer sounds compelling but feels difficult to verify.
This brings me to my broader questions for the experts:

1. What is the correct caseback engraving on an original military-issued 1550 SG — "BUND", "BUNDESWEHR", or can both exist? and what about the concentric marks of the left one? the stamping appears to have been redone at a later date

2. Regarding the 3H red symbol on the dial — I have noticed significant variation in its size and position across different examples. Is there a definitive guide to the known authentic variations, and which are the most desirable among serious collectors?

3. How do you personally distinguish an unpolished original caseback from one that has been refinished or replaced? The concentric turning marks on Watch #2 raised a red flag for me.
4. Every seller claims full originality. Where does the truth actually lie, and what are the non-negotiable details an expert checks first?
I will attach photos of both watches.
Any insight from this community would be invaluable before I commit to a purchase at this level.
Thank you in advance.