Hi Wild

Which part of Sydney will you be sailing? Have you met Ben Cutmore? He sails on Pittwater.

Get yourself a copy of the "Building Rules & Regulations" at the
NMCC web site.
They are not too daunting and you will find answers to many questions there. For instance, rule 13.5, the bridle height must be a minimum of 380mmm above the deck. In practise, not all sloops go this low. Some aim to be level with the boom gooseneck.