Tips on using VDOT as a % of threshold pace?

Greetings,

Is there a known rule of thumb to adapt to VDOT system to a min/max % of threshold speed?

For example - an 18min 5k will give a VDOT of 56.3 and the following training pace to follow per zone

Easy 7:29 ~ 8:15
Marathon 6:35
Threshold 6:13
Interval 5:43
Repetition 5:19

However I’d like these values to be a % of min/max of threshold such that I can use TrainingPeaks Workout Builders to automatically set a min/max pace per zone that i can push to my Garmin. I can follow a marathon pace from my watch which is between lets say 6:25 and 6:45 and dont want to have to follow just 6:35 coz pace fluctuates based on terrain.