HIM plan from BT (longest run / bike recommendation)

I believe most of the BT plans are "time-based".  So my recommendation would be to run the planned TIME and not worry about the distance.

If your Oly volumes are high, why don't you instead import a HIM plan instead of a bridge plan?  And see if those volumes match up better?

Make sure you look at the whole training load (volume + intensity) in deciding whether it is really less.  That said, if you are comfortable at the higher level, there is no reason to step down to what the canned plan says.

Your 55-60 mile rides will be 'enough' as long as you ride them solidly (not lots of coasting/chatting/stopping).  Doing one or two "over-distance" rides may help you from a confidence perspective, though probably unnecessary from a strict fitness perspective.  So your call.

You can probably say the same thing about the longer runs.  As long as you can handle it, I think there are some benefits to running up to/over the race distance.  But that depends how you recover, your pace, etc.  the plan probably goes off of time.  I would probably just say stick pretty close to that without knowing more.