Ha, when I read the title, I thought you were starting a thread to talk about foreign currency exchange rates! Like NOK -> USD :riding:
718mm is too short to maintain the proper riding geometry and it could adversely affect the handling of the bike. If you can find a way to lower the back end and return to a balanced stance front to rear, then the 718mm forks might be usable. Otherwise, you'll want to stay with as close as possible to the length of the original Showa forks. You should search for a set of Suzuki GSX-R600 USD forks which are in the range you stated (735mm) but also have a steering bearing diameter and steering shaft length very close to that used on the BMW. That's important to consider.