I don’t know what the contents of the Big Mountain training plan are, but based on your test results, I would be tempted to skew more of the workout mix toward your Zone 1 and Zone 2 intensities. I think that’ll give you the biggest long-term benefit.
The description in the test recommended 80% at this intensity with 20% at higher intensities. 80% should be the bare minimum, even in well-trained athletes. 90% would be even better. Even world-class athletes train with the same distribution.
In addition, if you’ll be going to altitude, you’ll want your AeT to be as high as possible. From what I understand, at altitude there isn’t enough oxygen available to allow for an intensity high enough to recruit fast twitch muscle fiber. So you’ll only have access to slow twitch fiber which is best trained below AeT.
On your next test, I would recommend getting some lactate samples below 140. The typical limit for AeT in most people is around ~2 mM, rather than 2.5, which is usually considered the upper most limit for purely aerobic work. With no readings below that level, it’s hard to tell if lactate was indeed plateaued at 2.5 during your test.
In short, I would avoid Zone 3 training until your AeT (~2 mM) is around 90% of anaerobic threshold. If AnT is at ~160, then you’ll want to get AeT up to at least ~145 before adding any threshold work.
I hope that helps.