Those are some long bricks you are putting in. With it comes (IMHO) great risk and little reward. A good IM run is largely due to great bike fitness and the ability to hold way back during the race (bike leg). Add in a good volume (and frequency) of running in the year before (not six weeks) and excellent body composition (key) and you are on the right track.
Here is a good way to think about it. If you show up at IM with a bike goal in mind then you are probably going to have a substandard run. Bike split goals always lead to bad run splits. You have to give yourself permission to hold back and trust that your running will move you through the field.
Those big bricks are a little bit scary. You may want to re-think them.