If we assume that the 2pt conversion is 50%, the XP is 100% and that winning in OT is 50%...
Going for 2 on the first TD will result in a win 62.5% of the time. Going for 2 after the 2nd TD wins 50% of the time, and kicking the XPs result in a win 50% of the time.
Late and Trailing: Always Go For 2 Down Eight After a Touchdown – Predictive Football