Hi Jan,
I think that may be a system that’s not seen too often. There are so many different shock systems out there with each having there little ‘tricks’ when it comes to replacing the spring. I looked it up in the Bestfit Cat. and it has it listed as ‘Forster New’. You may have better luck (I don’t know for sure) trying to find the spring by referencing that name and the Bestfit part # just in case it’s used on watches other than Forster…that is if you lose or break the one you have. Of course that’s not going to happen! 
My guess is that exchanging it with an incabloc system might be a challenge. You would need to find a system that matched all of the dimensions of the one you have or modify the plate and bal. cock to accept the new system. There would possibly be other issues too. You can check the dimensions at the Incabloc website at http://www.incabloc.ch/incabloc_en.html if you decide this is something you would like to try.
If you already left for your vacation and check the forum during your travels then HAVE A GREAT VACATION Jan!
Bob