To replace heart rate with power in any of our training plans you will need to establish your zones using power.
Wear your power meter while conducting the HR drift test to find your aerobic threshold. Using some numbers to illustrate my point. Let’s say you see a 3% upward drift in HR when starting the test at 150 bpm. It is a safe bet that the power you produce to run at a pace that elicits a 150bpm HR and its speed is your aerobic threshold power. So, for Z2 runs you will want to keep your power under that number. If you are training on very hilly terrain you should also do a drift test running or hiking steeply uphill and use the power number you find as your hill power. Flatter and steeper are very likely to give different AeT power numbers.
Similarly, you can conduct our AnT test for both flatter running and steeper hiking to find your AnT power numbers which I predict will be different.
It is not trivial to do all this but it mainly just takes time. Power SHOULD be a better way of measuring ad controlling the training effect you are seeking.
I hope this helps.
Scott