How was the crossing to Australia? Is your Cal equipped with wind-vane steering? If so, what type is it and how did it perform for you. I'd be interested in knowing more about your boats set-up and outfitting.
I also have a Cal 39 (1982 MRK III) that my wife and I are sailing in Mexico. One of the issues we had when we purchased the boat was deterioration of the headliner around some of the opening ports due to minor leakage, as well as overall deterioration due to aging. We looked into options for restoration and opted to use upholstered sectional panels. These were attached to 1" fir strips (the coach roof was divided along the width into four sections), which were glued and screwed into the roof. The panels were constructed of 1/8" marine plywood covered with thin foam padding and marine grade Naugahyde. These were attached to the fir strips using industrial grade Velcro self-adhesive strips which were attached to both the fir strips and upholstered panels with staples.
The panels stopped at the bulkhead that separates the main salon from the vee-berth. The area covering the sidewalls was padded and glued in place and extended from the outboard side of the cabin overhead hand rails to under the galley (starboard; to the overhead teak rail above the cabinets and shelf) and tucked as far under the remaining cabinets above the nav-station and those in the salon. The underside of the upper cabinets (two on each side of the salon) and the pair of open shelves (two per side) were individually treated with fir strips and custom fitted upholstered pieces.
The hull of the quarter berth was also covered, gluing it in place and the overhead was put in place using the panel approach.
Taking time to layout the fir strips and cutting the plywood panels to fit (breaking the length up into two pieces) is time consuming and requires attention to detail (especially around the hatch opening and mast opening). With the padding and upholstery stretched around these panels, you'll find when doing the final installation the reveals around each of the panels will be tight and look great. The trim pieces at the ends of the cabin and those around the hatchway and mast will also serve to hide the finished ends of each of the panels. You'll have to reshape some of these to insure room for the panels to be sandwiched to the roof top.
It is a moderately large project to undertake, but the advantage is that it provides a warm interior; adds to noise suppression; hides wiring and hardware attachment points on the coach roof; and, is easily removed for any changes to hardware or wiring.
There is a discussion here in Sailnet you might be interested in reading. It can be found here: Head liner replacement help - Cruisers & Sailing Forums
Good luck. I'd be interested in hearing more about your boat and the progress you're making.