SQ421 can I suggest you something like this. I'm not sure if the HKG-ORD will operate in time with your schedule, but instead of going to JFK.
AMM-LHR-SYD-PER-NRT-DEL-HKG-BOM-HKG-ORD-ANC-DFW-BOS-LAX-LHR-MCT-AMM
Or you can change BOS to JFK (fly the 3 class transcon to LAX) This will push over 59k BIS miles
This will work over the summer when the ANC flights are operating....
AMM-LHR-SYD-PER-NRT-DEL-HKG-BOM-HKG-JFK-DFW-ANC-DFW-SJU-LAX-LHR-MCT
61k BIS