Outstanding job!
"But there are several operations to transform it like that: shaving of the rear side, cutting of the groove and shaping of the case back seat."
For anyone needing to tell at a glance if a 1016 case is genuine (or a very good copy), look for the slight groove around the case where the case back seats as noted by Rolojack. Since it is hard to duplicate, not many replicas or Frankensteins will have it. No guarantees though.
Here is a picture showing the groove in a 1960 model along with the '4th grader' lettering on the case band, original brass reversers, and butterfly rotor weight:
https://www.hqmilton.com/timepieces/j0ngylog/1960-rolex-explorer-1-1016-3748
No telling how much someone paid for this watch but a 1016 of this year model and in the same condition would have been around $1000/$1500 25 years ago.
Now they are $10k to $20k! Imho this is a good reason to stick one together with a JMB etc case and Eta for an everyday watch.
Another reason...you see dozens of 'bezel watches' (submariners) here and there but almost never a 1016.
What's the down side?
They look like Air Kings.
"The 1560 mvmt is a pleasant surprise!!
Yes it is.
I have most of the parts to put one together but can not find a suitable case. Thought about having a genuine 162xx case modified and re-lettered but do not have the right connections. Have a couple 162xx cases with lug holes and since they were made for a 3135, a no date 1560/70 will fit right in one. The dial seat is the right size for a 1016 dial and the groove for the case back gasket is cut in the case like a 1016. Also have a couple nos tritium dials and hand sets plus crowns, crystals etc. The case would need the lug tops (aka 'shoulders') thinned down, the groove cut around the back of the case like 1016 cases, a bezel cut for a 25-22 crystal, and new numbers/letters. Finding a properly stamped case back would also be a problem.
Another catch...my 1570 no hack movement has the letter 'D' at the beginning of the serial number and the 'D' means it was originally a Date movement.
I've had the parts for 20+ years, They were just gathered up as 'parts' and not intended for a '1016' project but now the 1016 is Hot.
Should have bought a 1016 back then.
...and a 6263 or two.
Passed on a 6263 all apart but complete for $1600 waaay back.