Learning to scale for yourself is a skill. It requires understanding both the purpose of the workout as a whole and the purpose of the movements within the workout. Diane for the professional athletes is a sprint.
– Dan Bailey set a new world record in Diane with a 1:35 time.
– Kristan Clever set a new world record on Diane with 1:54 time.
If we compare these scores to running, these are competitive 600m times for a good high school athlete running a sprint. So this means Diane is a relatively all-out effort with almost unbroken form. This means the movements should be less than 80% of your 1RM, and probably less that 65-70% of your 1RM for you to blast through them while also maintaining good form.
Men: To perform the workout as prescribed, you should have a 1RM deadlift of 325lbs (225 is roughly 70%).
Women: To perform the workout as prescribed, you should have a 1RM deadlift of 200lbs (135 is roughly 70%).
As far as the handstand push ups, in order to do Diane as written, you should be able to do single set of twenty handstand push ups while fully rested. If you can’t perform that many, then you will really pay for it in the second and third round of the workout.