bump

You could do a 30 minute swim , 2 hr bike then run an hour at projected pace and use that.

I would expect to ride about 10-15 bpm lower than your LT for your HIM ride. Perhaps even lower if you are a low mileage athlete.

HiM should be z3 effort.

Z2 bike, start you run at top of z2 and settle in low z3 for the first half. Let it rip the last 5k.

You can use your info however you should set lower ranges as others have posted.

Reason being is the buildup of fatigue, you would have spent Time in the swim, time on the bike, by the time you get to the run you may not be able to sustain your LTHR. 30 minute workouts do not compare to 5 HR races.
In practice- Do a swim at race pace then see if you hit the same LTHR on the bike, then same for the run your numbers should be lower to sustain effort.
Happy Training!