How to get permanent residency for Australia from Britain?

My first love from UK and I have met after 45 years and would like to eventually marry and retire together in Melbourne. I am an Australian citizen, how and what is the easiest way to do this? He will have three pensions so will not require any help from the Australian government.Should I sponsor him or should we apply for a permanent visa? We are both a little confused. I hope someone can help. Thankyou