Hi all,
This camera it's finished, client did the tests and he has back a Super Ikonta 533/16 with a clear viewfinder with a perfect rangefinder.
About ungluing, 1 hour inside a jar with water at 180 degrees were enough to unglue it.
Full pictorial:
https://flic.kr/s/aHskQZxP8F
Now I have a Super Ikonta 532/16 and a prism from a 531/2, I will try to match them and make the rangefinder work again

Thank you, all, for the advices.
Alex