Cooper said he wants to swap codes and give the 13-man game "a fair crack" with Williams, a good friend of his, at the Toronto Wolfpack before the pair retire.
"I want to play with Sonny before we both retire. But I wouldn't mind playing NRL either, just for one season or even just come and do some training with the lads to see what it is like," Cooper said on the Ice Project podcast.
"If it doesn't happen, it doesn't happen. I am happy with what I have been able to achieve, but if the opportunity arose I would love to do it."