Thanks Jack,
Southern Cross mowers are very much a passion of mine, particularly the 4-stroke models.
I purchased the collection from a local bloke who had been collecting Southern Cross parts for most of his life. A quantity of the parts had already been sold before I purchased them. For the most part everything was still labelled or in the original Southern Cross parts envelopes. Of course the years have taken their toll and some parts have gone a bit rusty or tarnished, some of the labels have torn or faded, and the jute string had rotted off. Silverfish had left their mark too in places, etc. But for the most part everything is still in good condition and the labels readable.
One thing I meant to add in my first post is I realized the two adapter parts had to fit together because the adapter (KX-C60) still had the old chute (KX-C61) attached. But it did not look much like the new parts until I took a closer look. The original chute part had been used so much that it was broken, rusted and buckled. Nevertheless it was easy to tell it was the same part.
I cannot be 100% sure about the rear guard, but it definitely would form a good fit at that location on the KXC base, and this seems very likely given that it was in with a whole box of Southern Cross mower parts. It is just a pity the part number had not still been attached to it when I found it.