65 minute is plenty. I did it for SYD-SIN-FUK 2 months ago with 50 minutes connection.
Admittedly SYD-SIN flight was late, which meant I only had 30 minutes transit. Even with the inter-terminal trains, I still had to run from T2 to furthest gate at T3 (given the size of the terminals) and just made to FUK flight. Amazingly, the luggage actually made it too!