I have existing SQ221 PE departing 8:40pm from SIN on VA award. I am planning to book HKG SQ Y flight to SIN separately on AC award. SQ 883 arrives at SIN at 18:15, meaning transit at SIN for 2:25hr. Is this enough time for transit on separate ticket? Or I should book SQ875 arriving at SIN at 16:30 (transit for 4:10) instead?
Note: There is a later flight SQ893 which arrives at SIN on 7:50pm (50m transit) which I thought would be too tight on separate ticket.