Be careful to not get too caught up in the numbers. With all the data we can collect it is tempting to try to really nail down to impossible precision levels.
I assume you are quoting the rates of climb you do from data collected off the treadmill. Those are only comparable to and useful for hiking on the treadmill and do not translate to the hiking out doors. Could you do 2000ft/hr (assuming HR= 123) for 2 hours on the treadmill? You can probably take the AeT HR and AnT HR from the tests but I don’t think you can use the speeds or rates of climb outdoors.
From the AeT to AnT spread I would say you do have some base work to do to elevate the AeT HR.
There is no metric that I know of to transfer FTP to HR at AnT.