Here’s the thing about Lowdown, it’s basically the background cast of Rush plus or minus a few people.
You’ve got Ash, of course, Senior Constable Michael Richard Sandrelli in Rush and the very sexy Dylan Hunt in Lowdown.
Adam Zwar is Alex Burchill (main guy) in Lowdown and he also played Marty Gero in season 1 and 2 of Rush.
Paul Denny played Bob in Lowdown and was ‘Aztec Patterned Jumper’ in season 3 of Rush.
Patrick Brammall was in season 2 of Lowdown and was of course Milos Fink, the motorist in season 2 episode 10 who was very upset to be arrested and ranted about why he was driving along the streets he was before confirming TR’s suspicions and leading them straight to the bad guys and Michael. He was a great character. Unfortunately Michael just ran off before they could have a scene together.
Matthew Dyktynski was in Lowdown and (unfortunately) in Rush. He was in the horrible episodes that I refuse to accept as canon (season 4 ep 7 and 8) as Yuri Gringko. I believe he was responsible for firing the first shot.
Charlotte Gregg was in a couple of episodes of Lowdown and Shay in Rush (the woman who stole the baby in season 2).
Cindy Waddingham played Andrea in Lowdown and was also in my all time favourite episode of Rush, season 3 ep 22.
Martin Sharpe was also in Lowdown season 1 and played a few characters over the years on Rush. You might also recognise him from Ash’s episode of Mr & Mrs Murder or you might recognise him name from The Crimson Room.
As you mentioned, Antony Starr was in season 2 of Lowdown and of course played Charlie ‘Dickhead’ Lewis on Rush.
Kate Jenkinson was in Lowdown and also played Leon’s girlfriend, Nina, in season 1 and 2 of Rush.
Alethea Jones was in Lowdown and season 2 of Rush. She also directed The Humble Beginnings of the Balloon (the ad for Tropfest that Ash was in).
Emily Wheaton was in Lowdown and also played Amber in season 4 of Rush.
Luke Arnold was season 2 of Lowdown and he played Constable Elliot Ryan in season 2 of Rush.
Natalie O’Donnell was in Lowdown season 2 and Rush season 3.
Scott Brennan is another one who was in Lowdown and Rush.
Anthony Ahern was also in both Lowdown and Rush.
Nicole Gulasekharam was in season 1 of Lowdown and season 2 of Rush.
Daniela Farinacci was in season 2 of Lowdown and season 1 of Rush.
Justin Fleming was in season 1 of Lowdown and played ‘Peroxide’ in season 3 of Rush.
Sullivan Stapleton was in season 1 of Lowdown and season 1 of Rush.
Steve Bastoni was in season 2 of Lowdown and season 3 of Rush.
Nicholas Bell was in Lowdown and season 4 of Rush.
Sonya Suares was in Lowdown and the very first episode of Rush.
Melissa Andersen was in Lowdown and season 2 of Rush.
Paul Moder was in Lowdown and season 3 of Rush.
Tony Nikolakopoulos was in Lowdown and season 3 of Rush.
Andy McPhee was in Lowdown and season 2 of Rush.
Fantine Banulski was in Lowdown and was also in season 3 of Rush.
Brendan Guerin was in Lowdown and Rush and also did stunts for both of them.
Frank Magree was in Lowdown and season 2 and 3 of Rush.
James Campbell was in season 1 of Lowdown and season 2 of Rush.
Damian Rocher was in season 1 of Lowdown and season 2 of Rush.
Christopher Brown was in Lowdown season 2 and Rush season 3.
Eddy Scott was in Lowdown season 1 and seasons 1 and 4 of Rush.
Bryce Hardy was in Lowdown and Rush season 2 and 3 as a couple of characters (including the infamous naked driver).
Rod Mullinar was in Lowdown and Rush season 2.
Martin Copping was in Lowdown and season 1 of Rush.
Aaron Farrugia was in Lowdown and also worked on Rush.
As you can see, there are a lot of crossovers. I will admit I didn’t spot all of those people in both shows (thanks IMDB!) but I did spot of a lot of them. The cast of 12 Angry People (a script reading that I went to a few years ago) was also mostly taken from the Rush/Lowdown casts. A lot of people in Lowdown have also worked on other shows that Ash has been in (The Pacific, The Slap, Mr & Mrs Murder etc) but I didn’t mention all of those otherwise this would have taken forever.