Dean,

what do you want to do?
IP timing: by RIV method set to 15 deg ATDC.

Your explanation describes the setting of the TDC sensor in the balancer, which is 20 deg ATDC.
This set up is only made in case the engine was disassembled to adjust the sensor to the correct crankshaft position. Only for dynamic timing this TDC sensor is used.

Tom