Via Sistina is one of five Turnbull Stakes entries for Waller, who trained five of the six winners of the race between 2015 and 2020.
Buckaroo will be having his first start since his dominant three-and-a-half-length win in the Group 1 Underwood Stakes (1800m) and Waller said that the gelding was racing for a spot in the $5 million Cox Plate (2040m).
"He'd have to win again…keep winning and you're in the Cox Plate, simple as that," Waller said.
"It's going to be a good race, so you want horses in good form."
Joao Moreira, who partnered Buckaroo in the Underwood Stakes, will again be aboard in the Turnbull Stakes.
Waller also has Cups hopefuls Valiant King and Francesco Guardi nominated, with the latter also entered for The Lexus Bart Cummings (2500m), while Atishu will take her place with Waller confident the step up to 2000m will see an improved performance third-up.
"She was a touch plain first-up, second-up she was a touch plain, but she will come on with those runs and be ready for 2000 metres now," Waller said.
The Waller quintet is among 23 entries for the TAB Turnbull Stakes with Eliyass, Warmonger, Fawkner Park, Place Du Carrousel and one-time Melbourne Cup favourite Circle Of Fire also nominated.