21-15-9 reps of:
225 pound Deadlift
Scaling for handstand push-ups can be any version of box handstand pushups, abMats under head, or dumbell presses. Whatever you do, it better be hard if you want to get stronger (think 3-5 reps before resting). It is better to go heavier with the deadlift than faster. Choose a weight which you can handle for all 45 reps, and move at a pace which allows you to maintain technique.
If you are capable of doing this workout fast, then take a long warm-up to prime the nervous system.
Post what time you plan on coming to the gym to comments.