According to the global Solas website there are 2 authorized dealers in Oz. Just Propellers in WA and All Marine spares in NSW.
You could try calling the head office in Taiwan for tech support.
Another suggestion is a dealer of the engines you have, they may be able to assist.
Finally try one of the facebook pages such as Australian Powered Cats, there will likely be other KC 5.2 owners with similar setup to yours.
I'm sure there will be others on this forum with same or similar setup too.
I have suzuki props made by Solas. Whilst they are stamped 20 pitch, it is impossible using the prop slip calculator I.e. it comes back - 6% slip. Suggesting stamped at 20 but are actually 22.
Cheers Adam