The last time the Aussie nationals were held in Perth (just about the most remote city on earth) was in 1988. Darren Clark had an injury to a hamstring muscle and was given medical exemption, but took his chances. As it was, Miles Murphy set a national record 44.72 (something like that) and there were some other good guys on the rise then too including Rob Stone and Mark Garner. Stone eventually ran 44.9 and Garner ran 45-flat and was a Tokyo 91 world 400m finalist. There was also Rob Ballard who was never short of effort or self-confidence. So it was a gamble to skip the Nationals in an Olympic year.
As for the Clark 300m time trial, it was his fitness trial to earn belated selection in the 1984 LA Olympic team. Clark was also injured and missed the 1984 Olympic selection trials.
But I understand Clark started his 300m at the right place in lane 5, then entered the curve in lane 3 and came off the curve into the home straight back in lane 5. He smahsed the Commonwealth record and almost also the World 300m record. The clowns at the finish line never knew a thing about it. So they announced Clark had passed his fitness test with flying colours and everyone lived happily in their pompous ignorance ever after. LOL. What a larf it all is…!