But Williams won't ride the stayer in his first few lead-up races.
The lightly raced Darren Weir-trained import is unbeaten in Australia from five starts.
Kings Will Dream kicks off his Cup campaign in Saturday's PB Lawrence Stakes at Caulfield with Williams scheduled to jump aboard on race day at the five-year-old's fourth start of the preparation.
“Obviously Johnny is an integral rider within the (Weir) stable and does a lot of education on the horses and he's not the easiest horse to get along with,” Spicer said.
“Johnny has done all the work on him last time around through trials and track gallops and Darren just feels that's the best option going forward.
“Craig can have a sit on him in the Turnbull and get the feel of him then hopefully into the Caulfield Cup after that.”
Williams won the Caulfield Cup on Southern Speed in 2011 and Dunaden in 2012.
Kings Will Dream is at $8.50 in the TAB's Caulfield Cup market with Ace High and Emotionless on the second line at $15.
The Caulfield Cup (2400m) is on October 20.